This music comes from Left 4 Dead, Valve's co-op zombie shooter released in 2008, and is tied to the Tank, one of the game's most dangerous Special Infected. Players learned to recognize the cue as a warning that a brutal encounter had started. Outside the game, the track spread through gaming edits, streams, and short memes because it communicates danger faster than dialogue. It is still used when creators want the same kind of alarm-signal energy as a danger alarm sound effect meme.