The episode: “Earth vs. The Spider,” ep. 313
The riff: Corrected by Tom as the hero prepares to enter a dangerous cave and his girlfriend says that people who have gone in there “haven’t come out again.”
The explanation: The riff is a reference to Mark Twain’s classic “The Adventures of Tom Sawyer.” Injun Joe is a half native American antagonist in the novel, the main danger to Tom and his friend Huckleberry Finn. Together with his criminal compatriots, Injun Joe hides out in a cave outside of town, where he also buries some treasure that Tom and Huck are eventually able to acquire.
Novelty factor: Knew it all the way. Twain was some of the only stuff that we were made to read in English classes that I ever genuinely enjoyed.
NOTE: I couldn’t find much that I liked as a representation of Injun Joe, so please enjoy this insane 8-bit version of Injun Joe’s cave, which features what appears to be Injun Joe riding a dinosaur as he menaces Tom Sawyer.