lewd, indecent recorded from 1840 (in form blueness, in an essay of Carlyle's); the sense connection is unclear, and is opposite to that in blue laws (q.v.). John Mactaggart's "Scottish Gallovidian Encyclopedia" (1824) containing odd words he had learned while growing up in Galloway and elsewhere in Scotland, has an entry for Thread o'Blue, "any little smutty touch in song-singing, chatting, or piece of writing." Farmer ["Slang and Its Analogues Past and Present," 1890] offers the theory that this meaning derives from the blue dress uniforms issued to harlots in houses of correction, but he writes that the earlier slang authority John Camden Hotten "suggests it as coming from the French Bibliothque Bleu, a series of books of very questionable character," and adds, from Hotten, that, "Books or conversation of an entirely opposite nature are said to be Brown or Quakerish, i.e., serious, grave, decent." Exhausted from anger, strain, or other great effort. For example, You can argue until you're blue in the face, but I refuse to go . This expression alludes to the bluish skin color resulting from lack of oxygen, which presumably might result from talking until one was breathless. See also under talk one's arm off .