Which South Park episode was this?

Several years ago, there was an episode of South Park where Cartman admitted to having a compulsion: If he hears the beginning of “Come Sail Away” by Styx, he can’t concentrate on anything else until he’s sung it all the way through.

What episode was this? Until I find out, it’s just going to eat at me the way the need to hear the song all the way through eats at Cartman!

Thank you in advance.

Season 2: Cartman’s Mom is a Dirty Slut. Cite.

Amazing, Dooku! Thank you!