The episode: “Manos: The Hands of Fate,” ep. 424
The riff: Deadpanned by Joel as two sheriffs break up a heavy petting session between two teens parked in a car on the side of the road.
The explanation: This is a word gag and sly reference to the 1974 independent film “Macon County Line,” which was apparently about “a vengeful county sheriff out for blood after his wife is brutally killed by a pair of drifters.” The film was presented as a “true story” despite being completely fabricated. The “Macon County” in the title has nothing to do with the one in Illinois where I happen to live–the story takes place somewhere in the South.
Novelty factor: I recognized the nature of the joke when I heard it because I am familiar with the title of “Macon County Line,” but I’ve never seen the film. I’m impressed at the way they combined the film’s subject matter (a sheriff) with wordplay (“make-out” instead of “Macon”). Just an average example of the silly humor of the MST3k writers.