•used to express disbelief and doubt in the trueness of something that someone has said
Etimoloji
Rhyme, literally, “blather, [O] blabbermouth, provided [that it is for a] long [time]”, probably of folk origin. First attested in the 1832–1883, but in common usage only as of 1843, popularized by Pieśń o ziemi naszéj (“Song about Our Land”) by Polish writer Wincenty Pol.