"Bad Little Boy" is the eleventh episode of the fifth season of the American animated television series Adventure Time. The episode was written and storyboarded by Cole Sanchez and Rebecca Sugar, from a story by Sugar, Patrick McHale, Adam Muto, Kent Osborne, and series creator Pendleton Ward. The show follows the adventures of Finn (Jeremy Shada), a human boy, and his best friend and adoptive brother Jake (John DiMaggio), a dog with magical powers to change shape and grow and shrink at will. In this episode, Marceline (Olivia Olson) tells the Ice King (Tom Kenny) a fan fiction involving her genderswapped form Marshall Lee (Donald Glover).