The Grim Adventures of Billy & Mandy
The Grim Adventures of Billy & Mandy
Smarten Up! (2x16)
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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.