The Aristocrats
For anyone not familiar with this movie, it's a documentary of sorts about this one particular vaudeville joke that comedians have been telling each other for ages. The punchline and the basic scenario are always the same but the rest of the joke is completely improvised by the person telling it, with the goal of being as offensive and funny as possible. Anyway, I say it's a documentary
of sorts because all it really is is 80 or 90 minutes of tons of different comedians giving their own spin on the joke. That may sound like it would get old, but believe me it doesn't. I thought the movie was hysterically funny.