Single lane onramp. A lot of people in line for the onramp (20+). I'm about 15 cars away from the onramp light. Chevy Tahoe with custom paint job (low-rider culture, maybe) five cars behind gets out of the line and tries to go onto the shoulder and what remains of the 2->1 lane thing. I move my car over to the edge of the wide lane so that he can't be a bitch.
He tailgates me, honks at me, I flip him the bird. He parks his car, runs after me, catches up (he's a bit heavy) and kicks the rear end of my car, I put my car into reverse and start to reverse after him to get him to get away (at this point he looks like he's going to actually come up to my car window), he backs up, and then I go forward again... he chases me again... (we're on an onramp, so I don't have anywhere to go because there's cars ahead of me) catches up and, I have my windows down (enjoying the fresh air!), grabs me and throws a punch at me. He just grazes me (I don't really have anywhere to go but I do my test Ali impression), tries to throw another and grab me but I speed up. At that point, he runs back to his car and gets past the cars and runs off the onramp. (Where we had got it opened up again) He takes the first exit and I don't pursue.
While he ran back to his car, I called 911... which is horrible in San Jose. It goes on for 30 seconds in Spanish, takes about a whole minute before I reach an operator... and then I tell them what little I remember about the car and the plates.