The Grim Adventures of Billy & Mandy

Smarten Up! (2x16)

Air date: Jul 18, 2003

Billy is worried about failing an upcoming Math test, so Grim gives him a "bookworm", which will make him much smarter. However, Milkshakes, Billy's cat, eats the worm instead, and is forced to tutor Billy. In the end, Billy is still an idiot.