The origin of this mlmlmlml clip is unknown, and it circulates simply as a short mouth-noise effect shared between soundboards and short video edits. Its appeal comes from how clearly the sound translates a tongue-out gesture even without video, so creators can add attitude to a still image or a silent reaction. It is often grouped with other raspberry, blah blah and tongue trill sounds, and it stays popular because it is brief, wordless and understood across languages as playful mocking rather than a real insult.