Where I come from those are fighting words.
Fighting words is a figure of speech. Under the law, no insult justifies a violent response. Period. Of course if the words are a threat of imminent violence, thats a different matter. Even so, the response must be proportional: if I threaten to throw a nerd ball at you, you cant pull out a gun and shoot me. Its the same principle: the law does not regard violence as proportional to insulting words