The joke begins when a performer walks into a talent office seeking work. An agent asks him about his act, so the performer explains it in the most vulgar terms including descriptions of body functions and sex acts. The punchline comes when the agent asks what the act is called. The performer answers: "The Aristocrats."

As punchlines go, it's not that funny. But the way some comics describe the act makes audiences howl. Others, however, won't repeat the joke, and still more startle audiences with a retelling that seems to be pulled from real life. What emerges is a sort of portrait of comedians at work and at play.

"It's like giving 100 canvasses to 100 painters and saying paint this nude person," said Bob Saget, the former star of wholesome TV comedy Full House. "Some people won't paint it because it's a nude person. Some people will paint it incredibly sexually; some people will paint it covered up. Some will paint it deviantly," he said.