The sound comes from Call of Duty: Modern Warfare 2, released in 2009, where earning 25 kills without dying unlocked the tactical nuke, the game's most powerful killstreak, and triggered this urgent ready notification. Clips of the alert spread through gameplay montages, reaction videos and memes, where it became shorthand for an unstoppable final move rather than just a match event. Like other competitive shooter callouts such as enemy spotted and bomb has been planted, it still works because players instantly recognise the stakes it signals.