The Merciless Pepper of Quetzalacatenango, also known as the Guatemalan Insanity Pepper, is an insanely hot type of pepper that Chief Wiggum serves in his chili at Springfield's Annual Chili Cook-Off.
Homer attends the Cook-Off and samples several different people's chilis, disdainfully critiquing them, and then arrives at Chief Wiggum's booth. Wiggum announces that for Homer, he has prepared an especially spicy concoction containing "The Merciless Peppers of Quetzalacatenango … grown deep in the jungle primeval by the inmates of a Guatemalan insane asylum." The peppers are so hot that Wiggum handles them only with tongs, and dons a welder's protective mask and gloves when he stirs his chili.
Homer's first attempt at eating the pepper gives him a burned tongue upon touching it with the tip, causing him to run around that resulted in him trying to douse his tongue with several mugs of beer at once only for Marge to mistake him trying for breaking a promise about not drinking beer during the Cook-Off. While downing glass after glass of what was presumably water, Homer nearly drinks a candle, which gives him an idea: He swishes the candle wax around the inside of his mouth, coating it and his tongue with wax, and then returns to Wiggum's booth.
Now protected by the candle wax, Homer is able to gulp down several Quetzalacatenangoes on his second attempt, shocking the crowd and even scaring Wiggum. However, shortly thereafter, he ends up experiencing a bad stomachache, followed by hallucinations to the point of psychosis. When a coyote appears in Homer's hallucination as his spirit guide and tells him there's a lesson he needs to learn, Homer immediately -- but incorrectly -- concludes that the coyote means "laying off the insanity peppers."
- "Quetzal" is a Central American bird and the currency of Guatemala.
- "Quetzalcoatl" was an Aztec deity.
- "Tenango" means "land of" in the Quiché language.
- Acatenango is a volcano in Guatemala.
- Quetzaltenango, also known as "Xela," is the second-largest city in Guatemala.
- When Homer returns to retry the Insanity Pepper with the protection of wax, Chief Wiggum, after addressing him as the big baby, mockingly states "Oh, my porridge is too hot! Oh, wawawa!" This is a reference to Goldilocks and the Three Bears, when Goldilocks consumes part of Papa Bear's porridge and discovers it to be far too hot for her tastes.
- When running to Ned Flanders for help, Homer begins to hallucinate, and one of the phrases that Ned says is "Gabba gabba gabba gabba hey", which is a reference to a Ramones song "Pinhead". Also sampled in Shpongle's "The Nebbish Route".
- Johnny Cash voices Homer's spirit animal.