>>>Don't get yourself into that sort of situation in the first place<<<
Think about where you're going: if your friends are going to a bar or other location infamous for "fights", stay home with a good book...any of WLP's titles will do nicely. If you're there already, Stay alert! Find and keep track of the exits, as well as the Restrooms. Leave if things start getting tingly (those hairs on the back of your neck? They really DO work as a trouble sensor, since they use a different set of protocols to feel for troubles about to start.) If you DO get into it, Kris' father is right: Don't run! That will attract trouble to you, as you become "Prey" by running, in a lot of cases. Fill your fist with something if you have to use it (I have a change purse/key holder that holds about 4-5oz of change and fits into my palm: very effective). And whatever else you do: key it to getting out of there a.s.a.p.

And a personal hint from a retired "Dirty Tricks" professional: Stay Low Key! Gym or Dojo T-shirts are good for the Gym or Dojo...noplace else!
Defer, back down, laugh, buy a drink/food/soda; anything to un-tension the atmosphere. Testosterone overload will get your ass whipped, do not try to be the Alpha Male (or Female), because that's what the Cops think they are, and they do NOT welcome challengers (even as "helpers").
Nuf' said?