[Unique 5.7]

In my state, I would yell, "He's gonna kill him!" REALLY loud and as panicky as possible at the 3rd head punch. I would then pull and most likely kill the perp with 3 center of body mass shots. Then I'd probably puke and shake all over. (I stabbed a man in the femoral artery in self defense in 1970, almost killed him, and that was my reaction about ten minutes later. And, yes, people stood impotently around watching this.) Then, I'd lawyer up and pray my clean arrest record, age, military experience, 35 years of holding a job, witnessess there, and character witnessess would help me avoid legal trouble.
If I was unarmed, I would run out of the place yelling for a cop and looking for a phone. I do not have the skills and strength to fight that guy. BTW, just to let you know I am NO hero, a major motive for running out would be to spare myself injury.