1
general::
Very angry, as in When she locked me out I was really browned off. This expression originated as Royal Air Force slang for "disgusted" and "depressed" in the late 1930s and had crossed the Atlantic by World War II. It gradually came to be used more widely as a slangy synonym for "infuriated." One theory for its origin, mentioned by Eric Partridge in his slang dictionary, is that it alludes to brass buttons on a uniform turning brown from lack of polishing. Partridge noted, however, that the ‘‘predominant Army opinion" was that the word had the same literal meaning as buggered.
American Heritage Idioms