This sound is associated with Lion, an operator from Tom Clancy's Rainbow Six Siege by Ubisoft. In the game, Lion's EE-ONE-D scan warns players not to move or risk being detected, which made the audio memorable far beyond normal match sounds. It spread through Rainbow Six clips, YouTube edits and short meme videos because the warning instantly communicates pressure and exposure. It is still popular in gaming content for moments that need the same kind of detected, hunted, or high-alert feeling as an enemy spotted callout.