Police sirens have long been used on emergency vehicles to clear traffic and warn people nearby, with the wailing tone designed to be heard from far away and to change pitch so drivers can locate it. As a recorded sound effect, the siren became a staple of films, television crime dramas and later online videos. Creators now reuse it far beyond realistic scenes, dropping it into memes and edits as a shorthand for trouble, being caught, or an exaggerated emergency, which keeps the clip in constant circulation on soundboards.