That's not what you said earlier.
I'm not BasilBrush, so there's no "what I said earlier" to speak of. What *I* am saying, however, is that speaking of walking up to someone and yelling "motherfucker" is missing BasilBrush's point, because the word's function in that particular context is that of a whole sentence. Saying what amounts to "you regularly have sex with your own mother!" is what might get you clobbered, not the word itself. Walk up to a person and yell "motherfucker!" while pointing at someone else and the person who was in one case so offended as to break your nose might actually laugh about it with you instead.