The Musical of Musicals: The Musical is a pretty friggin great one. It tells one story: a woman can't pay her rent, is harassed by the evil landlord, gets advice from her older friend/confidante, and then is saved by the handsome leading man. But the story is told 5 different ways with 5 different composers and the style that they do their shows: Rodgers and Hammerstein ("Corn!"), Stephen Sondheim ("A Little Complex"), Jerry Herman ("Dear Abby!"), Andrew Lloyd Webber ("Aspects of Junita"), and Kander and Ebb ("Speakeasy").
Many, many, many, many references to musical theatre and those composers shows. Some pretty broad, others rather obscure. My favorite joke is in regards to ALW's style, the narrator says the stage direction: The set changes to Junita's boyfriend Billy's apartment. The audience applauds....the set change.
"Sing the words, Patti!!!!" Stephen Sondheim to Patti LuPone.