For those interested in the sexual/scatological side of the man's work, this song is a definitive highlight. This one is all about the banal and the mundane. "Why Does It Hurt When I Pee?" asks the main character in the 1979 album Joe's Garage. Well, he caught gonorrhea (his "balls feel like a pair of maracas") from a waitress named Lucille -- that's why. But this topic is backed by a pompous rock pastiche, with prog rock-ish symphonic overtones. The grandiosity of the instrumentation (including tympani!) and arrangements (with an opera-like instrumental section) make for a laugh riot.
The piece was written in the summer of 1978 and was inspired by tour manager Phil Kaufman's unrequested question. In an interview, Kaufman attested that Frank Zappa wrote the song while on the bus immediately after he jokingly uttered the sentence and had the musicians play it the same night (whether this story is true or false is left to your decision). One thing is sure: "Why Does It Hurt When I Pee?" predates most of the material on Joe's Garage. In order to fit it in the concept album, Zappa had to completely shift story lines. The instrumental "Toad-O Line" triggered a change from the story of Mary becoming a crew slut and ending up in a wet T-shirt contest, to Joe's ill-fated relationship with the waitress.
The song quickly became a live favorite and was featured in all of Zappa's subsequent tours. Starting in 1980 it would always be performed after "Joe's Garage." One of the best (and most outrageous) renditions is documented on You Can't Do That on Stage Anymore, Vol. 3.