As much as I hate to condone kicking someone while they are done, it has to be done. If you are in a situation like that, you have to make the statement, "**** with me and I'll **** you up just like this guy". And you have to do it fast. If you take your time with it you look weak. Talk to much, you look weak. Posture to much, you look weak.
Of course it's better to avoid the situation all togeather.