Premise: "The Aristocrats" (also called "The Debonaires" or "The Sophisticates" in some tellings) is a taboo-defying off-color joke that has been told by numerous stand-up comedians since the vaudeville era. The joke was the subject of a 2005 documentary film of the same name. It received publicity when it was used by Gilbert Gottfried during the Friars' Club roast of Hugh Hefner in September 2001.
Hypothesis: Gilbert Gottfried has never participated in a Friar's Club roast.