Less Than Hero - Fry is trying to take is pants off because he's too scared to give his wallet to the Mugger and Andrew.

"My wallet is stuck! Here, I'll just give you my pants!"

Or something along those lines

Average family guy, youtube, "thumbnail."

I think it's the episode where Fry gets worms that make him super smart and buff. Parasites Lost, season 3 ep 2.