While reading the Guide to the Good Life I came across this gem on dealing with insults:

Refusing to respond to an insult is, paradoxically, one of the most effective responses possible. For one thing, as Seneca points out, our nonresponse can be quite disconcerting to the insulter, who will wonder whether or not we understood his insult. Furthermore, we are robbing him of the pleasure of having upset us, and he is likely to be upset as a result.

Notice, too, that by not responding to an insulter, we are showing him and anyone who is watching that we simply don’t have time for the childish behavior of this person. If a humorous response to an insult shows that we don’t take the insulter seriously, a nonresponse to an insult makes it look as if we are indifferent to the existence of the insulter: Not only don’t we take him seriously, but we don’t take him at all! No one wants to be ignored, though, and the insulter is likely to feel humiliated by our failure to respond to him—not with a counter insult, not even with humor!