Used to describe discontent. Especially if you just realized you seriously screwed something up. Usually used at the begining of a sentence, but can be used at the end again to make sure your discontent is clear or for more effect. Example: Arg! I spent three hours doing this essay question and I did the wrong one. Arg!
ARG
Meaning of ARG in English
Slang English vocab. Английский сленговый словарь. 2012