When given multiple explanations, the oddest possibility is the most likely one.
A trope mostly in comedic works where, when given multiple explanations for an event, the oddest one is most likely is going to be true. The inverse of Occams Razor. As such, it can be summarized as "When you hear hoofbeats, think zebras, not horses." The name is a take off of Occams Razor, combined with Arkham, the fictional city from the works of HP Lovecraft (which is closely tied to the idea of madness or surprise). Often used as a form of Bait And Switch. The audience, expecting Occams Razor, writes off the wacky explanations as not possible only to be surprised that the outlandish possibility was correct. Genre Savvy viewers will have expected the Arkhams Razor to be in effect from the get go and expect the unexpected, so to speak. See also: Infallible Babble, Cassandra Truth. Often overlaps with The Cuckoolander Was Right or Refuge In Audacity. Compare Impossibly Mundane Explanation, where an explanation floated by a character is dismissed for being too mundane.
- Thanks to a related trope, Bat Deduction, some of the Riddler's riddles work this way. For a relatively grounded example, his first-ever crime used the clue "banquet," sending Batman and the police to a charity dinner. The real, and much less conventional meaning of the clue was that the Riddler had flooded a bank vault -- gotten a "bank wet" -- to defeat its pressure-sensitive locking mechanism and was looting it in scuba gear.
- In an episode of How I Met Your Mother the gang is arguing about who was the most "badass" as a kid. All of their tales of youthful rebellion are eventually proven false, except for Team Mom (and literal mom) and kindergarten teacher Lily, who painted a picture of herself as basically an Expy of Omar. Naturally, at the end of the episode this is proven true.
- Double-subverted in Community when the study group cannot work out what happened to Annie's missing pen. Unwilling to believe any of the group stole it, they agree to believe Troy's manufactured story that a ghost took it. In fact, it was Troy's escaped pet monkey, Annie's Boobs.
- Interestingly used as part of how the Weirdness Censor is justified on early seasons of Buffy The Vampire Slayer, where the police (who know the truth about the town's vampire problem) have little trouble convincing most people that the vampires are just PCP addicts. As Oz points out when he's told the real story, the vampire explanation actually makes more sense.
- Often played non-comedically in House. In medical jargon, an unexpected diagnosis is referred to a "zebra," and this occurs so frequently in the show that it even has a page on the House Wiki. At one point the title character says "I look for zebras because the other doctors already ruled out all the horses."
- In one comic of Questionable Content, Marten and his girlfriend Dora take a long lunch, and return with Marten wearing some of Dora's clothes. Their friends immediately assume that they had done something naughty, but Marten claimed that they had been ambushed by Shaolin Monks and spilled spaghetti sauce on his clothes and needed to change at Dora's. Everyone laughs it off, but a few strips later he is proven correct when a battered monk arrives at the coffeeshop and recognizes Marten.
- Also occurs in the explanation for Steve's infrequent appearances for a long stretch of the comic. The two possible explanations were "he got drunk and dicked around for a while" or "he became a secret agent and blew up an island," and it was implied that not even he knew for sure which was true. Until later, when he ran across The Baroness from his story.
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