Let me start by stating I was only witness to the events which developed quite close to me on the Subway. It was 6 pm and everybody just wanted to get home. Not enough trains and to many people.
One of three girls who's sitting next to me sprayed foam into another girls hair who was in the process of getting of the train. There was something brewing so it wasn't completely unexpected. The girl turns around and after two seconds of screaming starts attacking the girl with the foam can. Her friends jump in and it becomes a scrawling mess right next to me. I can't be bothered. I'm watching TED on my iPhone.
Only after a big guy pulls them apart and I see the faces of the rest of the people in the cart I realize my newyorkerness of indifference is not really shared.