Bait-and-Switch

A type of setup where a character leads the audience or other characters into thinking they are going to say or do something, but says or does something unexpected. This is usually a joke, and if the punch line of the joke causes the first part to take on a new meaning (e.g., "I just flew in from Chicago, and boy are my arms tired"), it is technically called a "paraprosdokian." Note that this trope doesn't have to be Played for Laughs; serious examples exist as well. In Dialogue, Arson, Murder, and Jaywalking is one example. The first two words raise the expectation of another crime, equally severe, but then switch it out with jaywalking. The origin of the name comes from a now-illegal advertising practice in which a store would bait a customer into their store with an advertisement featuring a product selling for a reduced price, but when the customer got there, they would find out that they were "all out" of the advertised product... but the store would be happy to sell a similar product for just a few dollars more, thus performing the switch. Can be a form of Subverted Trope, or a Double Subverted Trope if the thing being switched is a trope in itself. Sometimes turns into a Brick Joke if there's a later payoff. Compare Does This Remind You of Anything?, where the audience is meant to think about how a situation is similar to another situation, but without ever believing that it is the other situation. Related to Anti-Humor. This can also happen in film trailers and commercials as well.