The Aristocrats, a documentary by magician/comic Penn Gillette and comedian Paul Provenza, follows the genesis of "the filthiest joke ever told." The real joke is, it's not a joke -- the "humor" comes in how the joke is told, and the dirtier the better.
The filmmakers explore how comedians tell the joke to their fellow professional funny folks, and how the most outrageous permutations of the "shaggy dog"-style narrative lay bare some fundamental truths about the nature of humor and the values society truly holds sacred.
Plus, telling the joke well can be pretty funny, in a very scatological way. Elizabeth Blair explores the dark world of comedy.
George Carlin shares his version of "The Aristocrats" joke.