The line comes from Half-Life 2, Valve's 2004 first-person shooter, where scientist characters react to danger and intruders in the game's research facilities. Short, quotable NPC lines like this one were later clipped for soundboards and video edits because they carry a complete attitude in barely a second. It remains useful because the command is instantly understood without context, making it an easy shorthand for dismissal in gaming videos, reaction edits, and meme compilations.