With no clear credited source, lulululululululu spread as a user shared soundboard clip valued purely for its absurd loop. Short looping vocal noises like this travel easily between edits because they need no context, language or setup to land. Creators reuse it as a shorthand for brain empty silliness, mock celebration or playful taunting, and its near five second length makes it long enough to fill a scene without needing to be repeated or explained.