I think there was a bit once on Third Rock from the Sun where two of the aliens go to a party in Sonny and Cher drag. When asked who they’re supposed to be, one answers: “Julius and Ethel Rosenberg; but we think they may have given us the wrong costumes at the shop.”

It would be kind of fun to do a “most unguessable costume” party: “Hey, it’s the Defenestration of Prague! And look, isn’t that the Love That Dare Not Speak Its Name, over by the punch bowl?”