I try embracing stoicism. One stoic strategy is to agree with your attacker. It throws them completely off. Take what they say, and agree with the most exaggerated form you can.
Example:
Bully: You're so ret*d.
Stoic: How kind of you to notice. You're right of course, it took me half an hour to tie my shoes this morning. Still, we all must carry on with what we are given.