Smarten Up! The Grim Adventures of Billy & Mandy : Season 2 Episode 16
TV-Y7-FV Cartoon Network 30m int(0)
Aired: July 18th, 2003 @ 8:30 PM EST on Cartoon Network
Billy is worried about failing an upcoming Math test, so Grim gives him a "bookworm", which will make him much smarter. Milkshakes, Billy's cat, eats the worm instead, and is forced to tutor Billy. Billy is still an idiot in the end.