This is a generic hush or shushing sound rather than a clearly attributable quote from a specific film, show or meme source. Clips like this spread widely through reaction edits, short-form videos and chat forwards because the meaning is universal and instantly understood. Creators keep using it because it works as both a literal quiet-down cue and a playful way to interrupt someone on screen. Its simplicity also makes it easy to drop into comedy, prank and awkward pause edits without any extra setup.