Give them a response they never saw coming. Next time they throw something at you say," yep, I did that, and I'm sure I'm not the only person who's done that. But most importantly I know not to do it again and if you wanna keep throwing that in my face, fine. But that says more about you than me doesn't it?" And leave them to answer that. But don't stay long enough to hear what they have to say because the last thing you need is to be burned. Good luck