The Grim Adventures of Billy and Mandy: Bearded Billy/The Nerve

"Bearded Billy" Billy tries to take an example from his father, who hates to shave, but does it because his mother likes it. So he gets some hair tonic. But unfortunately it makes him grow into a hairy sasquatch. "The Nerve" Billy wants to steal Mandy's nerve so that he can stand up to Sperg. So Grim shrinks Billy and puts her inside of Mandy's ear where he steals Mandy's tough nerve.