The episode: “Master Ninja I,” ep. 322
The riff: Spoken in a low voice by Joel as ninja Lee Van Cleef (a good guy in this film) clashes with three ninjas in head-to-toe black in a very dark room.
The explanation: All the black silhouettes (besides looking like an early version of that scene from Kill Bill: Part 1) have a very modern dance feel to them, hence the reference to Martha Graham. She was a choreographer with vast, sweeping influence over the whole of modern dance in a career that stretched for more than 70 years. The Martha Graham School of Contemporary Dance still performs today.
Novelty factor: Never heard of her, actually, but that’s not too surprising as my knowledge of the world of dance is just about zip.