Team Fortress 2, Valve's team-based shooter released in 2007, gives each class a set of short voice lines, and the Scout's warning about the enemy Spy became one of its most quoted alerts. The Spy class can disguise as teammates and stab from behind, so calling him out is a core part of matches. Clips of the shout later spread through gameplay videos, memes, and soundboards, where it moved beyond TF2 matches into general jokes about impostors, traitors, and hidden enemies. Its brevity keeps it useful as a fast reaction sound.