In the dark weeks following 9/11, Comedy Central’s management surprisingly decided not to cancel its taping of The Friar's Club Roast of Hugh Hefner. During the recording of the event, hundreds of comedians and urban luminaries found themselves shocked out of their post-terrorism pall by none other than Gilbert Gottfried, who delivered what the New York Times' Frank Rich, an attendee of the taping, called "the greatest dirty joke ever told."

Tracing its origins to vaudeville, this "comic's joke" is tantamount to a secret handshake among comedians and their friends. Although versions vary widely, it basically goes like this: A man seeking show biz representation walks into a talent agent's office and describes his family's act, which consists of various illegal and unspeakable activities including incest, bestiality, necrophilia, and an explosion of bodily fluids. After the man finishes, the appalled agent asks what this horrible act is called, to which the man responds, "The Aristocrats!"

And so it is that in the era of the FCC's war on indecency, veteran comedians Paul Provenza and Penn Jillette (the latter of daring comedy-magic legends Penn & Teller) have crafted a mighty unusual 90-minute documentary entirely about this joke. In a tightly edited montage of clips, more than 100 professional funny-makers from Robin Williams to Phyllis Diller, Hank Azaria to Fred Willard, Chris Rock to the Smothers Brothers, tell the joke, de-construct the joke, reconstruct the joke, and turn the joke inside out.

The genius of "The Aristocrats," the joke, is its free form. While the beginning and punchline are pretty much constant (with some variations mentioned by the documentary's players), it's the middle that provides a blank sketchpad for the warped mind of the comic. And the genius of The Aristocrats, the movie, is watching A-listers, B-listers, Borscht Belters, sitcom stars, writers, and even a mime put their filthy spins on the gag. What results is insanely profane, offensively vile, and almost unrelentingly hilarious. Want to know where your taste boundaries lie? Take notes.

Highlights of The Aristocrats include Bob Saget's disgusting take on the joke, told in the moments before he is to perform in a club; a hysterical animated version delivered by Eric Cartman of South Park, Kevin Pollak telling the joke as Christopher Walken; and Gottfried's clip from the Hefner roast, which if actually broadcast would have spurred a pile of legislation higher than the Catskills.

By the time Sarah Silverman – who rivals only Gottfried himself for fearlessness – makes an appearance, we’re too softened up by the verbal extremities to be shocked. (Her first-person version, which includes a toxic accusation against old TV personality Joe Franklin, is one of the funniest moments in the movie.)

The Aristocrats is naturally not for everyone. But if you're the type of comedy club patron who guffaws at the type of dark and edgy material that makes the suburban bachelorette partiers at the next table stare into their margaritas, you'll cherish this voyeuristic peek into the sick minds that make America laugh.

The DVD includes commentary track from Provenza and Jillette, extended scenes with many of the comedians, additional jokes (there are others?), and footage of the winners of some Aristocrats contest.