The chime comes from the passenger call system used on commercial airliners, where a single or double ding alerts passengers and crew before intercom messages and when seatbelt signs change. Airlines adopted the electronic tone because it stays clear over cabin noise without startling travellers. Online, creators borrowed the exact same ping for travel parodies, flight simulator videos and everyday announcement memes, where hearing it out of context on a bus, in a classroom or at home is the joke.