The episode: “The Magic Sword,” ep. 411
The riff: Spoken in a Peter Graves-type voice by Crow, right after one of the brave and heroic knights laments, “It’s too hot up ahead, they’ll be burnt to a crisp by this time.”
The explanation: This is one of many variations on this particular riff in the series, a running joke that is a reference to the TV show “Sea Hunt,” which aired from 1958-1961. The show starred Lloyd Bridges, who you might remember as the glue-sniffing tower controller from “Airplane!”, as a scuba diver for hire who had undersea adventures. In an odd coincidence, his character was named “Mike Nelson,” the same as MST3k’s future host. The line was common on the show because as a scuba diver, getting his air supply cut off was really one of the only dangers Nelson could face in every episode. As such, Bridges narration would say “By this time, my lungs were aching for air.”
Novelty factor: This was a riff that I looked up long ago, because it appears in many episodes. It seems to have been a favorite phrase of the cast and crew of the SOL in its early years. I like how this instance of it tweaks the regular dialogue into something new.