The phrase is everyday Brazilian Portuguese slang, with mto as a shortened spelling of muito, meaning very, and meu used as a casual way to address a friend. Short voice lines like this circulate widely as WhatsApp audios and soundboard clips because they capture a complete reaction in about two seconds. Users share it as a ready made sarcastic comment, especially among Portuguese speaking audiences, and editors reuse it across memes, gaming clips and chat compilations where a quick verbal eye roll is funnier than typing an explanation or adding a longer reaction track.