Dave the Barbarian (2004)

S1E27 Lederhosen of Doom

Fang receives a pair of pants from her parents but skips reading the accompanying note. This oversight becomes a major issue, as the note reveals that the pants are actually the evil trouser beast, capable of dominating anyone who puts them on. Initially, Fang adores the pants for the incredible strength they provide—finally, she matches Dave's power! However, it doesn't take long before the pants seize control of her, turning her into a weapon for their vendetta against their nemesis, Oswidge.