The phrase comes from Counter-Strike: Global Offensive, the long-running tactical shooter in which SAS operatives appear as a counter-terrorist faction. Short agent voice lines like this one are easy to lift from gameplay, and this particular delivery has circulated on soundboards and in edited clips because it works as a universal setup line. It does not depend on a specific map or match, so creators keep returning to it whenever a moment needs a calm, slightly knowing start before the action unfolds.