Because it is just a single, everyday utterance, this uh clip has no single famous source to trace, and that is part of why it travels so easily online. Creators lift short reaction noises like this from everyday speech, reuse them as a shorthand for doubt or delay, and pass them around in memes, edits, and group chats. Its vagueness is useful: without a fixed character or scene attached, anyone can drop it into a new context and let the surrounding video supply the joke.