Dance of the Sugar Plum Fairy

"Dance of the Sugar Plum Fairy" is a variation from the ballet The Nutcracker by Pyotr Tchaikovsky. It was played during the Season Four episode "A Very Crappy Christmas".

Background
The boys walk through a sewer to search for Mr. Hankey, as he hasn't shown up yet. Meanwhile, Cartman sneezes on Kyle's back and Kyle yells in disgust. Cartman then notes how it's ironic that Kyle is grossed out by that instead of the fact that he's walking in human feces.