21. "I Know What You Diddily-Iddily-Did" (Treehouse Of Horror X, 1999)
After Marge inadvertently kills Ned Flanders with her car, the family attempts to cover up the murder by fooling the town into thinking he had a heart attack. Soon enough, the family begins getting messages from someone claiming they know what really happened to Flanders. The I Know What You Did Last Summer movies haven't exactly been stellar, but at least we got a pretty good Treehouse Of Horror parody out of them.
Usually, topical parodies of terrible movies don’t age well, but "I Know What You Diddily-Iddily-Did" borrows enough good stuff from the horror genre to make sure that it will always feel fresh. This isn't one of those segments where seeing the original movie makes it any funnier; the episode relies on its own brand of humor to deliver the laughs, as opposed to depending on the source material.