January 27, 2005 -- PARK CITY, Utah - "The Aristocrats," the most talked-about - and probably the funniest - film at the Sundance Film Festival, is so filthy, it cannot be fully described in a newspaper.

The world premiere audience was screaming with laughter watching more than 100 famous comedians - including Robin Williams, Whoopi Goldberg and Jon Stewart - interpret a notorious routine that has been around since vaudeville, but reputedly has never been performed in public.

And with good reason. It's about a show business family demonstrating their routine - which breaks every possible taboo - for an agent.

When he asks what they call the act, comes the punch line: "the Aristocrats."

As interpreted by everyone from Phyllis Diller to Carrot Top, the particulars begin with graphic sexual acts, incest and rape, and are embellished by various comics with elaborate references to violence, various bodily fluids, outré props, racial and sexual epithets, and, in an animated sequence from the makers of "South Park," even jokes about 9/11.

Comedians Penn Jillette and Paul Provenza said they started shooting the documentary 31/2 years ago, strictly for comedian friends, but now theatrical distributors are expressing interest.

"Why not?" asked Michael Barker, co-president of Sony Pictures Classics. "What I saw was very funny." Jillette, the talkative half of Penn and Teller, says, "I was taken by the differences in style the way different comedians tell it, and the beauty is that it isn't a joke associated with anyone because it isn't told in public. It's the singer, not the song. It's like a jazz piece being interpreted by John Coltrane or Dizzy Gillespie."

He says that despite the extremely rough language, "the film has a gentle, loving feel. There's no violence, no nudity, no conflict. It's just people having a great time."

Provenza says the comics were given total creative freedom, though some versions of the story were cut for time and thematic reasons, and will turn up on the DVD.

"People tell dirty jokes everywhere, even in the red states," he said. "It's not just some crazy cult and it's not a smart guy/dumb guy thing. There's a reason people pay for porn and the Bible is free in your homeroom."

Jillette claims some comedians who wanted to participate, like Adam Sandler and Mike Nichols, weren't included because of scheduling conflicts on the film, which was shot cheaply on digital video.

"The Aristocrats is Johnny Carson's favorite joke, and he considered telling it for us, but decided he wanted to stay retired," said Jillette, "so we're dedicating the film to him."