The line comes from Portal, Valve's first-person puzzle game released in 2007, where automated Sentry Turrets guard test chambers and announce when they detect the player. Their polite yet menacing voice lines became one of the game's most quoted features, and clips of them spread through gameplay videos, memes and soundboards long after release. Today creators reuse the short announcement as a quick enemy spotted cue in edits, because its instantly recognisable game origin and deadpan delivery signal detection in under two seconds.