“Nuh uh” is an informal English refusal and disagreement phrase rather than a sound with a clearly documented single source. Short recordings of the phrase became common in reaction edits, meme compilations, short-form videos, and online replies because the wording is instantly understandable. Its popularity comes from the contrast between a tiny vocal response and an exaggerated visual or claim. The sound is especially useful when creators want a character or narrator to shut down an idea without adding a full sentence of dialogue.