Vai tomar no cú is a common Brazilian Portuguese insult, literally telling someone to go away in crude terms, and it circulates online as a short reaction sound rather than as a line from a named film or character. Brazilian creators use it in meme edits, short videos and forwarded voice messages to deliver a blunt, humorous shutdown, and its recognisability comes from everyday spoken Portuguese rather than a single viral origin. That everyday familiarity is why it still works as a quick insult in reaction content.