The episode: “Samson vs. The Vampire Women,” ep. 624
The riff: Realized out loud by Tom as a shirtless Mexican wrestler and bare-armed vampire size each other up and prepare to fight it out.
The explanation: Mapplethorpe was a famous American photographer who was known for his stylized black and white portraits of celebrities and nude men. Himself gay, Mapplethorpe’s provacatory work was controversial and raised questions about public funding of possibly objectionable art. He died at 42 from complications from AIDS, and the foundation created in his name continues to raise money for HIV research to this day.
Novelty factor: I didn’t know who Mapplethorpe was, but it was pretty clear from the context that he probably had something to do with the photography of muscly men. Another example of the MST3k writers’ versatility in riffing, drawing a reference from the fine arts world.