The episode: “Space Mutiny,” ep. 820
The riff: Delivered by Tom Servo after the movie’s villain, the extremely oily Commander Kalgan, shoots somebody dead with a laser gun.
The explanation: This joke is a sly reference to a famous ad campaign for Calgon-brand water softener in the 1970s-1980s. An overworked housewife-type would be overwhelmed by all the stresses in her day before proclaiming, “Calgon, take me away!” Then they would cut to her relaxing in a hot bath with her Calgon products, blissfully free of her burdensome family, presumably plotting their demise. Calgon water softener had another, equally famous series of commercials in which a Chinese laundromat operator claimed his “ancient Chinese secret” got clothing clean, but really it was Calgon. Racism at its most hilarious.
Novelty factor: I actually knew this one when I first heard it, because my mother apparently watched a lot of these Calgon ads. When I was growing up, the poor, stressed woman would jokingly put her hands on her head and say “Calgon, take me away!” None of us knew what she was talking about at the time, and thus pretty much ignored it.