Would I be smiling? No, more shaking my head in disbelief at the dipshit who walked up to me and said dumb shit about my Mum. Then I'd walk away. I'm sure some of the "real world" types will call that cowardly, I don't particularly care, I'm not into pummelling people in general. Someone tries to physically attack me or go after someone I care about, then it'll get physical. Until then, nah, name-calling isn't enough to 'fuck someone up' over.
Then again, I'm a white guy. I'd imagine it becomes a bit different when racial shit is involved. I've never had to live that, never had to endure it, so I can see that being the mother of all triggers.