Yeah, the case of "mistaken identity" or play on words was always good for a laugh. There was another one where they were watching a video of some blond singing...I think it was an effiminate male with very long blond hair...

Beavis: "Check it out, Butthead! That's that chick Debbie Gibson!"
Butthead: "Uh, no, Beavis....I think it's Olivia Newton's John"