Cartman on The Aristocrats
"'The Aristocrats' is a joke that has been with comedians since Vaudeville. 'The Aristocrats' is a joke that is never told in public."Here's a video (WMV) link to Cartman from South Park telling the Aristocrats joke. Do not click the link if you're offended by references to incest, paedophilia and jokes about 9/11.