Black Ops II, released in 2012, made the K-9 unit a memorable multiplayer scorestreak, sending an attack dog after opposing players until it was killed or timed out. The warning that one was loose became shorthand for sudden danger, and short clips of it later circulated in gaming edits and meme soundboards. Like an enemy spotted callout, it works because players instantly recognise the threat, even without seeing the match, which keeps the clip useful long after the game left its peak.