Coucou is a familiar French greeting, equivalent to hello or hey, and it is often used between friends in a light, informal way. As a short soundboard clip, Nathan Coucou circulates mainly as a personal greeting rather than a widely documented meme, shared in edits, streams and messages where a spoken hello feels warmer than text. Its appeal lies in its brevity and personality: at under four seconds it is easy to drop into an intro, a reaction or a joke without interrupting the flow, which is why creator communities keep reusing it for arrivals, callouts and playful introductions.