The Aristocrats?

Is this for real? Vanity Fair, August 2005, p. 40:

Culled from over 100 hours of interview, The Aristocrats, a new documentary from comedian Penn Jillette (Penn & Teller) and Paul Provenza, is devoted exclusively to a single joke, which, until now, was a secret rite of the stand-up circuit, performed only for comics by comics, after hours. And with good reason: its success hinges on the description of an imaginary scene so vicserally offensive that the listener is, in most cases stunned into laughter. ... [The joke] always ends with the same, deceptively tame punch line: "We're the aristocrats!"