Jeffy

"Why?"

- His catchphrase "Hey, my name is Jeffy, see it says it on my shirt, Jeff-y. Wanna see my Pencil? Wanna see it?"

- His greeting. This one specifically in Who Wants To Be A Millionaire? Episode 3 "(cries) You covered up my piggy plate with green beans, I don't even like green beans."

- The Hitman! Jeffy Jeffy (or shortly Jeffy ) was a major protagonist turned into the tertiary antagonist of the SML series (since Jeffy has been known to be antagonistic in videos like Jeffy's Bad Word). He portrays as a highly stupid kid who has a tendency to keep putting stuff in his nose, mainly pencils. He is reluctantly looked after by Mario and Rosalina, whom he refers to as "Daddy" and "Mommy", although neither of them have legally adopted him, as they are his foster parents.

Personality
Jeffy is flat-out retarded, outranking Tony, who hasn't been around in years. He has a bad habit of smacking his diaper, which strangely happens to be outside his pants. When he is called a "bad boy", he tends to throw a tantrum by throwing his head onto any surface, but  calms down when he is called a "good boy." His parents delivered him to Mario possibly because they were too annoyed by his unnatural stupidity and did not want to deal with him any further. Mario,  Chef Pee Pee, and possibly Cody  hate him, while  Junior  and  Joseph  think he's awesome after surviving a game of Russian Roulette once and  Rosalina  is more loving and caring towards him. Rosalina also acts like a motherly figure to Jeffy.

Jeffy, however, has been shown to act rather smart at times, such as in "Jeffy's Homework!" when he reasoned that 8-4=8,, since they are taking 4 out of the equation, even going on a profanity-laced rant. Later, in "Jeffy's Bedtime!", he called the nameless tall character in Green Eggs and Ham a liar, since the character claimed he liked the green eggs and ham, but the illustration clearly shows he didn't eat the ham at all. He used to live at 7 Jeffy before being dropped off at  Mario 's door. Jeffy also tends to soil himself sometimes. He also seems to like cheese on his green beans.

He has also shown a bratty side, as seen in "Jeffy's Bedtime!", where he demands that Mario and Rosalina make him green eggs and ham, and in "Jeffy Gets Potty Trained!", when he demands that Rosalina give him marshmallows instead of peas, also in "The Hitman!", where he refuses to his nuggets because they didnt gave him 20 toys and throws them away.

Likes

 * Pooping in his pants
 * Marshmallows
 * Playing his Cat Piano
 * Rosalina
 * Fun
 * Putting things in his nose
 * Toys
 * Prank Calls (in Jeffy's Cellphone!)
 * Saying "Faggot" (Jeffy no longer does that anymore)
 * Calling the Police
 * Mario
 * Pencils
 * Green Beans (with String Cheese)
 * Fruit Loops
 * Chuck E. Cheese (who Jeffy thinks is Mickey Mouse in Jeffy's Birthday!)
 * Mickey Mouse
 * Spanking his diaper
 * Feebee
 * Morse code (spanking his diaper)
 * The Bunny Do
 * Giraffes
 * Police
 * Mashed potatoes
 * Music playing in his new crib

Dislikes

 * Green Beans
 * Peas
 * Toilets, mainly when they're flushed (this frightens Jeffy)
 * Being called a "bad boy" or a "bad Jeffy"
 * Spankings
 * Animals
 * Bees
 * The Ticket Blaster (in Jeffy's Birthday!)
 * Basketballs (when they come into Jeffy's face, he screams)
 * Getting 'raped'
 * Mario (Sometimes)
 * The Bunny Do song stopping
 * Tai Chi Chasers
 * The Cantonese language
 * Black Yoshi (when he tried to kill him in Jeffy's Mistake!)

Mario
Mario is Jeffy's Guardian. Mario hates Jeffy while Jeffy likes Mario. Jeffy usually calls Mario "Daddy", even though Mario is not Jeffy's birth nor adopted father and keeps telling him he's not. Mario is incredibly unhappy that Jeffy was dropped off at his apartment door and loathes the fact he has custody of the little shit. Mario gets frustrated with Jeffy in nearly every video they appear in together. Most of the time however, it seems that Jeffy annoys Mario not on purpose. Mario has tried multiple times to get rid of Jeffy, but Jeffy ends up coming back after, or in the case of Where's Jeffy?, Mario goes back to get Jeffy because he had Rosalina's necklace. In  Bowser Junior's Nerf War!, Mario makes a small cameo appearance right at the end and attacks Jeffy with a Nerf Gun. Because of his overwhelming stupidity (or possible retardation), Jeffy gets Mario into trouble way too much to be considered funny.

Although Mario gets annoyed with Jeffy most of the time, he has been shown to care about Jeffy, as shown in Jeffy's Mistake! when Black Yoshi is about to kill Jeffy the first time. In Rosalina's Parents!, Mario freaks out upon seeing Jeffy gets abducted by aliens. It's possible Mario might only care just so Rosalina won't break up with him.

Chef Pee Pee
Jeffy seems to like Chef Pee Pee. Chef Pee Pee however does not seem to have patience for Jeffy, just like Mario. Chef Pee Pee was annoyed with Jeffy when Mario and him were trying to get Jeffy to eat his green beans. Chef Pee Pee also seemed upset when Jeffy ruined the pencil cake Chef Pee Pee made for him in Jeffy's Birthday!.

Rosalina
Jeffy and Rosalina seem to get along well. Jeffy usually calls Rosalina "Mommy" just like how he calls Mario "Daddy." In Jeffy Gets Potty Trained! though, it was shown at multiple points that Rosalina is finally starting to lose patience with Jeffy, becoming almost as frustrated with him as Mario as Jeffy refused to eat his peas, demanding marshmallows instead.

Brooklyn T. Guy
In Mario The Babysitter!, Brooklyn T. Guy (as a cop) doesn't seem to mind Jeffy. However in the third episode of  Who Wants To Be A Millionaire?, Brooklyn T. Guy is shown to get annoyed with Jeffy's behavior. Also Jeffy's The Dog/Kid for the family.

Bowser Junior
Bowser Junior thinks Jeffy is awesome for surviving Russian Roulette in Bowser Junior's Game Night 3. Jeffy also seems to like Bowser Junior. However, Jeffy did get upset at Bowser Junior when he knocked over the Lets Go Fishin' Board.

Joseph
Like Junior, Joseph thinks Jeffy is awesome for surviving Russian Roulette.

Cody
Jeffy seems to like Cody, but Cody doesn't seem to like Jeffy.When Jeffy smacked his diaper in Bowser Junior's Game Night 3, Cody seemed to like that and did it to himself. Cody however did seem to get annoyed with Jeffy as the video progressed. In Jeffy's Birthday!, Cody seems neutral with Jeffy and isn't shown to be annoyed with Jeffy.

Jeffy's Mom
Jeffy and his mom appear to most likely have a bad relationship, as his mom didn't want him around due to being annoyed by his sheer stupidity, which was why she dropped him off at Mario's apartment.

Jeffy's Dad
Not much is known about Jeffy's relationship with his dad, though it can be assumed that he was annoyed by Jeffy's stupidity, possibly causing Jeffy to be abandoned and left at Mario's residence. He is mentioned in in Bowser Junior's Game Night 3.

Feebee
In Jeffy's Sister!, it was revealed that Jeffy has a sister named Feebee. Jeffy and Feebee are very similar in character, with nearly the exact same traits. They can even communicate to each other through diaper patting, somehow. However, because she has, so far, only appeared in Jeffy's dream, some speculate that, because she was not dropped off along with Jeffy, Feebee is actually dead (or possibly never existed in the first place)

Reception
Jeffy is arguably the most panned SML character in the SML series. People truly criticize the fact that he bothers Mario in many of the videos that he appears in and also ruins characters like Rosalina. People have even suggested that Jeffy should go back with his real parents in a future SML video, getting rid of him permanently (a few have gone even far as to suggest killing him off), however, Logan seems to be doing this since he has been revealing more information about Jeffy and his family. Also, in Jeffy's Birthday!, it was revealed that he had a note in his pocket this whole time, revealing some information about him and there is an area of the letter that looks like it says "If lost, please call (whatever Jeffy's parents's phone number is)" meaning that he could return to his parents sometime soon.

Despite the character's negative reception received so far, other fans have argued that Jeffy's negative reception is mostly due to Jeffy's Bad Word!, in particular, which has gone on to become one of the most infamous and controversial SML Movies to date. They essentially argue that ever since the release of this controversial episode, that they automatically reject any episode that has Jeffy in it at all: for example, many fans point out that Jeffy haters complained about Rosalina's Parents! for having Jeffy in it, despite the fact that Jeffy only had about one minute of screen time and was not even the main focus of the episode.

Quotes

 * "My name is Jeffy. See? It says it on my shirt, Jeff-y."
 * "Wanna see my pencil?"
 * "Uh! Uh! Uh!"
 * "Someone pooped my pants."
 * "See my pencil? It can go up my nose."
 * "(Cries) I'm a bad boy?! (Bonks head on the nearest object)"
 * "I'm a bad boy?!"
 * "Why?"
 * "I want that for my nose! I got an extra hole!"
 * "It says I'm a good boy."
 * "Coloring book?"
 * "Hey. I'm a mummy."
 * "Where my pencil at? I lost my pencil!"
 * "Why did you take my crayon?"
 * "Hey, I found my pencil."
 * "Hey! I lost my crayon! Has anyone seen my crayon? It's yellow."
 * "Yeah, I want some gummies."
 * "Yeah, so it won't get dirty!"
 * "It's starting to itch."
 * "So I don't poop my pants!"
 * "It's smeared up my bath."
 * "I'm running out of toilet paper."
 * "Who's gonna wipe me?"
 * "(Cries) You said Jeffy's weird?! (Cries again)"
 * "(Cries) You said Jeffy being a bad boy?!"
 * "It feels good on my pee-pee."
 * "Feed me, I'm a Giraffe! Ah! (Pats his Mouth)"
 * "Gummy right here!"
 * "You said jeffy's a bad boy?" (Rams his head on the Border on the door)
 * "Well, my diaper's still clean."
 * "And my pants are dirty."
 * "Please wipe me."
 * "Daddy come wipe me."
 * "But I like the cheese on my green beans."
 * "If I wanna eat the money, I'm gonna eat the money."
 * "I don't like green beans!!!!"
 * "Want some more money?"
 * "Can I do brain surgery on you?"
 * "I'm just gonna use my pencil."
 * "He looks like my daddy."
 * "Ok, I get all the money!"
 * "My pencil broke off in my brain!"
 * "I knew that was the last bullet in there!"
 * "Yep, seriously need to shut up for now, right?"
 * "It won't fit!!!"
 * "Geemee!! (Cries) You took my hammer!"
 * "(Cries) You lost my toy!"
 * "Bunnies don't lay eggs."
 * "Bawk Bawk."
 * "I don't get to see the Easter Bunny! (Cries) I want to see the Easter Bunny!!"
 * "I love animals! My favorite animal is a carrot!"
 * "Where the f**k did you get that from? Because 4 is taken away so it's 8!"
 * "So it has another 4 when it does NOT exist somewhere within it!"
 * "No, that's a baby 4!"
 * "Two 4s do love each other and make a baby 4! But this one is gone away! It's taken away from this thing, see? Look, you cover it up!"
 * "No, it's not! Where the f**k did it go? Where did it come back that fast?"
 * "No, it's not. The 4 looks nothing like a 2! What, did they adopted?
 * "I pulled it out of my ass."
 * "8."
 * "F**K THIS HELMET! F**K THIS PENCIL! AND F**K THIS DIAPER! I WANNA F**KING KNOW WHERE THAT FOUR WENT! TO COME BACK THAT F**KING FAST TO BE MAKING ANOTHER EIGHT! ITS EIGHT MINUS FOUR! YOU TAKE THE FOUR AWAY, IT'S F**KING EIGHT! I DON'T CARE WHAT YOU SAY, F**K EISENHOWER, AND F**K OTHER THOSE PEOPLE, I-ITS F**KING EIGHT! TAKE THE FOUR AWAY FROM IT! TAKE THE FOUR OUT OF THE F**KING CARD! PUT AN EIGHT DOWN HERE IN THE SPACE IT'S AN EIGHT!﻿"
 * "Fwog."
 * "Daddy taught me."
 * "Because you have an 8 up there, and you take away the 4, so it's not there anymore and the 8's left, you know it's 8."
 * "Ummm...74."
 * "Gidaraffe."
 * "Gi-da-ra-ffe"
 * "Fa-wo-guhh!"
 * "OK. Z Y X W V U T S R Q P O N M L K J I H G F E D C B, A."
 * "A B C D E F G....AAHH!"
 * "Because they don't love each other on that card, that one is a regular zero and another zero so it's 2."
 * "It's 2."
 * "Umm...baby 2."
 * "Because you have a mommy 2, and a daddy 2, and they had a baby, and it's a baby 2.
 * "Because you have one zero, and another zero."
 * "If numbers don't matter, why are we doing it?"
 * "Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, Strawberry, 50 fifty."
 * "I like mashed potatoes!"
 * "I wanna call my dad."
 * "I wanna be a doctor. I wanna do brain surgery."
 * "Kawk Kawww! Kawk Kawww!"
 * "You left me at the park with a chicken nugget and you said, Good luck, Jeffy!"
 * "Happy Meal?"
 * "Ok, you gotta catch me!"
 * "Helmet misses Jeffy?"
 * "The park?"
 * "I didn't give it to the squirrel. YOU gave it to the squirrel!"
 * "No, the squirrels are adopted me. Jeffy don't need a helmet."
 * "No, I'm not get hurt. Jeffy good boy up here."
 * "This guy's a liar."
 * "But he hasn't even touched his ham yet."
 * "I want green eggs and ham! I want green eggs and ham!! I WANT GREEN EGGS AND HAM!!! (Beat's his head up!)"
 * "Yes, there is, he told me he was gonna poop in my jammies!"
 * "But you asked for your keys."
 * "Oh, I'm sorry, sir. You've had too many! I'm cutting you off!"
 * "I don't want my peas, I want marshmallows!"
 * "I think I can poop, I think I can poop let me do it."
 * "I think I can, I think I can daddy."
 * "But there's something touching my ball shack!"
 * "I wanna eat my poop!"
 * "I had to get some toilet paper. I ran out."
 * "But it has a scary face on it."
 * "I'm a piggy!"
 * "Yes I am, look at my nose!"
 * "Daddy, I found Dory!"
 * "(gasps) Daddy?!?! Where are you going daddy? Why you're not coming up? Why did the bubbles stop?"
 * "I want a Pokémon battle!"
 * "Cookie Monster, I choose you!"
 * "Cookie Monster, use Thunderbolt!"
 * "Um...Sesame Street!"
 * "Yay! I win!"
 * "Did I win?!"
 * "I lost!? (Cries)"
 * "What will I do with this one?"
 * "I'm stuck in the camera!?"
 * "AAAAH!!! I'M STUCK IN THE CAMERA DADDY! I NEED TO GET MYSELF OUT!! I HAVE TO GET MYSELF OUTTA THERE! OH MY GOD! (destroys the camera)"
 * "Hey, daddy I'm a piñata."
 * "Daddy, I can fly! I'm a bird!"
 * "Uuhh, uuuhhh, uuhh, AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAGH! (Sneezes)"
 * "Daddy! Daddy, help me, I don't know where I'm at! uh uh uh uh uh uh uh!"
 * "Fiverites."
 * "Fiverites, at the top!"
 * "(cries) Yes, you did know I was locked in the bathroom because you came up and slammed the door, and you said, "Shut up, little shit!"
 * "What doing?"
 * "Games on my phone?"
 * "And THEN I get to call the wee-woos!!"
 * "Are you a prostitute?"
 * "Hey. Um, this is really embarrassing, but, I'm stuck in the bathroom and there's no toilet paper!"
 * "Please hurry! It's starting to itch!"
 * "Oops, wrong number!"
 * "An iPhone?"
 * "Is Mr. Wall there?"
 * "Why would he do that?"
 * "Faggot."
 * "Daddy raped me!"
 * "Forget? HOW DO YOU FORGET RAPE!!!???!!!
 * "Have fun in prison. Don't get raped."
 * "What up, faggot? You wanna rape me again?"
 * "DADDY, YOU'RE A FAGGOT!!!!
 * "My butt hurts, Mommy."
 * "No, he stuck his fingers in my butt, and twirled them around and sniffed them."
 * "Well, my daddy, he uh, he kept putting his hands on my butt over and over again, and I screamed and I cried, but he didn't care he just kept doing it and doing it, and I cried and I cried and he said "YOU'RE GONNA TAKE IT!!!" And I took it. (Sobs)"
 * "DUN DUN DUN DUN DUN DUN DUN DUUUUUN! Pooperman's is here to save the day!"
 * "I'm digging my butt, Daddy!"
 * "Oh hey lady, do you need to be saved by Pooperman?"
 * "No one can resist Pooperman!"
 * "Hey, Who are you?"
 * "Grand Theft Auto? Xbox?"
 * "Oh hey, Mr. police officer man! What doing?"
 * "Oh no! I didn't mean to do that! Don't shoot!"
 * "I did do nothing! I did do nothing!"
 * "(Gasps when he sees the wasted screen) I died????? AAAAAAAAAHHHHHHHHH!!!!!!!!!!!!"
 * "Stupid Xbox!" (Throws it off the balcony)
 * "I'm sorry."
 * "Daddy, I pooped the bed. I pooped your bed, Daddy."
 * "But I don't wanna put my PJs on Daddy, I wanna sleep in my big boy pants!"
 * "Daddy, it's squishy!"
 * "But I want cereal, Daddy!"
 * "I want Froot Loops. With milk."
 * "Daddy's a f**king liar!"
 * "I pooped paper?"
 * "I want to go to Disney World, Daddy!"
 * "MICKEY MOUSE!!! MICKEY MOUSE!!! MICKEY MOUSE!!!"
 * "(Gasps) We're in Disney World? (Gasps) And there's Mickey Mouse on the sign!"
 * "Hey Mickey Mouse! What doing? I'm Jeffy!"
 * "Its my birthday and I'm at Disney World!"
 * "AAAHHH! I don't like bees, Mommy!"
 * "(Gasps) Stunt Master Jeffy?
 * "Oh I would like to play this game! Pick Jeffy to play this game!"
 * "Is this my cake?"
 * "CAKE?"
 * "(Gasps) Its a pee pee, Daddy!"
 * "Is that Jeffy on the card?"
 * "He's got a helmet just like Jeffy!"
 * "(Gasps) Its a big pencil, Daddy!"
 * "Am I a fish?"
 * "I want to go home!"
 * "There's a big scary monster in there that blew air!"
 * "(Gasps) MICKEY MOUSE!! AAAAAAHHHHHHHH!!!!"
 * "Mickey Mouse, I always wanted to see you Mr. Mickey Mouse!"
 * "Where's Minnie Mouse at?"
 * "It go in my butt, daddy."
 * "Daddy, can you help me put my Pooperman shirt on? I wanna wear it."
 * "I have a sister named Feebee!"
 * "Well, F**K THIS HELMET! AND F**K THIS PENCIL! AND F**K THIS DIAPER! THIS IS A HOT DOG!!"
 * "Daddy, I was just trying to show you my animal noises!"
 * "The Boogeyman doesn't go after kids with poopy pants, daddy?"
 * "Well, the Boogeyman's never gonna get me." (poops his pants again)
 * "First, you eat my cat piano, and then you wanna staple my eyelid shut."
 * "I took my morning poop, daddy."
 * "What kind of TV show is this, daddy?"
 * "Then why would they name it hot dog if it wasn't a real dog?"
 * "'Cause it's hot, and it's a dog. Hot dog."
 * "Say cheese? Take a picture?"
 * "I am happy!"
 * "Oh, hey daddy. I'm pooping in the toilet like a big boy."
 * "Oh. THAT'S why there's nothing in the toilet."
 * "Who's Feebee?"
 * "I don't got a sister."
 * "I'm not gonna lie for you, liar."
 * "Oh, that's Feebee."
 * "Oh, Feebee's my sister."
 * "Hey, uh... you got a crayon in your nose."
 * "By myself?"
 * "Can I poop in the sink?"
 * "Can I poop in the bathtub?"
 * "What's a store?"
 * "AHHHHHHHHHHHHHHHHHHHH!!!" (in Jeffy Goes To The Zoo!)
 * "Gidaraffe?"
 * "I wanna see a gidaraffe! Put jeffy see a gidaraffe!"
 * "Okay, faggot."
 * "What up, faggot?"
 * "A puzzle? What's a puzzle?"
 * "Um..daddy, I have a question about the puzzle."
 * "What would happen if a girl was sitting on the coffee table and I was sitting underneath it and she decided to poop on the table and it smeared across the glass and ran up her back, what would happen?"
 * "(Cries) where'd my Hop Hop go?!"
 * "I want my hop hop."
 * "Oh it's my bunny suit daddy."
 * "Daddy! Daddy! Daddy! I gotta poop, and I don't know where to go!"
 * "Harambe?"
 * "AAAAAAAAAAAAAAH AAAAAAAAAAH AHHH! HE EAT MY HAND OFF!"
 * "Hey Harambe!"
 * "Why you do that?"
 * "I don't even know."
 * "Daddy the monkey told me to he said "Come here Jeffy let me eat your butt".
 * Daddy you got me a piggy plate (Snorts)
 * "I want Jello!"
 * "OH, RAPE RAPE RAAAAAAAAAAAAAAAAAAPE!!!!!"
 * "it slipped."
 * "I'm talkin' 20 toys!"
 * "Daddy, what are we doing?"
 * "Is that a Dolphin?"
 * "Whoops!"
 * (cries) You said jeffy's a bad boy? (hits his head on the tree)
 * "UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUHHHHHHHHHHHHHH!!!!!!!!!!!!!"

Trivia

 * Jeffy is Exotropic and Hypertropic
 * Many fans complained by saying that Jeffy is offensive. Later, Logan stated that Jeffy is supposed to be funny like Chef Poo Poo, not mentally disabled. Others don't like Jeffy because he only exists to make poor Mario miserable and make stupid jokes. This is a mistake that Brooklyn T. Guy has made in Jeffy's Stupid Home Video!.
 * According to some fans, he is similar to I.R. Baboon from I Am Weasel as both like to put stuff in their noses. His scream also sounds somewhat like Homer Simpson's scream from The Simpsons. Jeffy appears in the video called "Jeffy from SuperMarioLogan in Khumba". Like Shrek, Jeffy has been breaking into the animated movie called Khumba and some of the other animals including the lead character of Khumba, however, are seeing him drive a helicopter. The video is made by MovieRide FX.
 * In the Pokémon series, Jeffy owns a Cookie Monster who can use Thunderbolt.
 * Despite being extremely stupid, Jeffy is still able to do many impressive acts, such as accurately painting the Mona Lisa on his Easter egg, finding a golden egg even though Mario threw it away, and say the full alphabet backwards.
 * Jeffy is first seen without his helmet in "Where's Jeffy?".
 * Jeffy sometimes speaks normally, and in 3rd person.
 * Jeffy is so far the only character to strike the same identical pose until "Jeffy's Mistake!".
 * His theme song is Doh De Oh by Kevin Macleod﻿.
 * Jeffy has his own facebook page, and an Instagram Page.
 * In Jeffy's Birthday, it is revealed that Jeffy's birthday is on August 21st.
 * The Jeffy puppet can be found on the Etsy website. The Jeffy puppet on Etsy costs $500.
 * Jeffy may understand morse code, as he communicates to Feebee by patting his diaper.
 * Jeffy is seen with his eyes bulging in Jeffy's Stupid Home Video!, Jeffy Sleepwalks!, Jeffy's Birthday!, Jeffy's Sister!, and more (including one eye).
 * On September 22nd, 2016 until September 27th, 2016, SML is selling Jeffy t-shirts for $19.99 USD and $26.11 Canadian dollars. This was revealed in Jeffy's Sister and the link for the website is on the description of Jeffy's Favorite Song.
 * Jeffy is believed to be the stupidest character in the entire series, possibly even stupider than Bowser Junior, but it's not confirmed.
 * In The New House!, it is revealed that Jeffy is extremely hyperactive, and requires medication to calm himself down.
 * This may not be the case, Mario hitting Jeffy might have traumatized him, and his voice and his hyperactivity may suggest that he went into an obsolete state of mind, and became very supersticious of Mario. The medication didn't work because it wasn't the work of his hyperactivity, it was most likely the work of Mario.
 * Jeffy is arguably one of the few children with true autism in the future and may be suffering from ADHD.

Poll
Do you like Jeffy Yes! No. Kind of. I am fine with him