The best thing to do is just to walk away. Most people who get in fights are stupid reasons anyways. And if the reason your doing BJJ/grappling is for street fights your in it for the wrong reason.
That's exactly what I'm saying. I honestly don't see how someone who trains as hard as I know I do can just go and start a fight with someone. I leave it all on the mat so I'm not concerned about starting street fights.
Just for example we were out at a club this weekend. One of the bouncers there called my wife a name thinking I couldn't hear him I guess. I could have walked over there and just started beating his ass sure, but I didn't. I walked over there and told him I heard what he said and that all I wanted was for him to go and apologize to my wife, otherwise I was gonna have to bring him out in the street and beat that ass. He went and apologized to my wife and when the cab came pick us up he even came out and opened the door for her.