Wear your best for your execution and stand dignified. Your last recourse against randomness is how you act — if you can’t control outcomes, you can control the elegance of your behaviour. You will always have the last word.
Kinda applies to dealing with shitty crowds, hecklers, bombing, etc. You can't control what happens, but you can control the way you handle the situation.
I hate when a comic's having a bad set and then turns on the audience (e.g. "You guys suck" or "Look at my fucking bicep!"). If you're gonna bitch at 'em, at least try to be funny about it or make a point. If not, suck it up, try to learn from it, and move on.