The sound comes from Valve's Half-Life games, where the shotgun's pump and lock became one of the series' most recognisable weapon cues, later heard again by players in Garry's Mod, which reuses Half-Life assets. Clips of it spread through gaming videos, memes, and edits that needed an instant signal that help, or a threat, had arrived. It remains popular because the cue needs no explanation: even viewers who have never played Half-Life recognise the pump shotgun sound as a warning that something serious is about to happen.