Air horns are loud pneumatic horns long used at sporting events, celebrations and on boats to grab attention over crowd noise. Online, the short, clean blast became a staple reaction sound in prank videos, sports edits and meme compilations, where a single honk can signal a win, a fail or an absurd twist. Its popularity has endured because the sound needs no explanation: listeners instantly recognise it as a signal to cheer, laugh or pay attention, and it works just as well in a two-second clip as in a longer edit.