PLOT: Jeffy dresses up as The Poop Monster for a (super-early) Halloween party at Joseph's backyard, with a new character replacing Cody (Cody just moved out). However, the ACTUAL Poop Monster has a huge battle with Jeffy at the Halloween party, angry at how Jeffy "mistreats" literal crap (doing it in the sink, doing it in jeans with diaper on the outside, etc) as The Poop Monster's "children" wanted to enjoy the "toilet ride experience" to the sewer systems.

Imagine being sad and angry because you didn't get to go on, or regret not riding, a cool rollercoaster.... and Junior, Joseph and the new boy gain crazy "Demon Slayer" supeerpowers....