The clip comes from user generated soundboard culture where short uwu voice lines are clipped and shared as standalone meme audio. UwU is internet slang for a cute facial expression, popular in anime and fandom spaces, and creators pair that soft delivery with an ordinary phrase like peanut butter for absurd contrast. With no clear original source, the sound spread purely as a reusable reaction, used in short form videos, edits and soundboards because it is brief, recognisable and easy to drop into almost any silly context.