The sound comes from the French dub of StarCraft 2, Blizzard's 2010 strategy game, where the Protoss Dark Templar answers commands with a grave 'oui'. French streamer Zerator reused the line on his ZeratorTV channel as the alert for viewer subscriptions, which is how the short clip spread beyond the game itself. Shared between fans as 'oui zera', it became a recognisable in-joke in French streaming circles and is now posted as a standalone reaction sound, separate from any gameplay, whenever a blunt but theatrical yes is needed.