Air horns were originally safety and signalling devices for boats, trucks and sporting events, valued because a single blast could be heard over a large crowd. Online, the sound took on a second life in the mid 2010s through MLG montage parodies and reaction videos, where creators layered it over dramatic moments for comic excess. It has stayed popular on soundboards and in short form edits ever since, used less as a real warning and more as a shared shorthand for hype, trolling and over the top celebration.