Guest-star 'Cesar Romero' plays the head of a trapeze troupe; moreover, he does his act as a clown. Romero's most infamous role is as the Joker, Clown Prince of Crime, in Batman (1966), whose second main hero, Robin had origin in a trapeze troupe with his family, The Flying Graysons.
Joseph alludes to incidents that happened in "The Flapjack Contest" (season 6, episode 15).