Usually-obscene joke about a performance act
"The Aristocrats" is a taboo-defying, off-color joke that has been told by numerous stand-up comedians and dates back to the vaudeville era. It relates the story of a family trying to get an agent to book their stage act, which is remarkably vulgar and offensive. The punch line reveals that they incongruously bill themselves as "The Aristocrats". When told to audiences who know the punch line, the... Wikipedia