The phrase traes puro sueño is everyday Spanish slang used at home and at work to call out someone who looks half asleep, with mijo adding a familiar, teasing tone. Online it spread as a short meme audio on Spanish language social feeds, where creators reuse the same line over new faces and situations. Its appeal is how ordinary it sounds, like a comment from real life rather than a scripted punchline, so it keeps working for school, work and late night clips.