The phrase comes from everyday Brazilian Portuguese slang, where miga is a shortened, affectionate form of amiga and ta magra comments that someone looks skinny. Clipped into a short audio, it spread online as a reusable reaction rather than as a line tied to a confirmed show or creator. People share it in chats, edits and short videos when they want a quick, recognisable compliment that also sounds like a joke, which keeps the sound circulating even without a single known origin.