R.E.P.O. is a cooperative horror game built around retrieving valuables while avoiding hostile creatures, and its short enemy spotted cues have become a shorthand for danger among players sharing clips online. The duck notice comes from that gameplay loop, marking the instant a creature becomes aware of a player rather than a scripted cutscene. As streamers and editors clipped those tense encounters, the half-second sound spread through gameplay videos and memes, where it still works because it instantly signals that a quiet run has just turned threatening.