Mr. Poopybutthole

He turns up at the Smith family's door already welcome, a floppy-limbed neighbor with a raspy catchphrase greeting who slides into the household's chaos without explanation or fuss. He wants little more than to hang around, crack jokes, and be part of whatever's happening, cheerful in a world built on dread.

He's a running joke that never explains itself, and that's the charm: a background gag repeated until it becomes oddly affectionate, voiced with loose, giggly warmth by Roiland. Against the show's nihilism and family dysfunction, his uncomplicated, unbothered presence lands as genuine comic relief rather than filler.