Yes, and it wasn't as cool as you might think.

I studied martial arts since I was three years old. One day I was getting off the subway car, and there was a man with a rollerbag walking ahead of me. A woman stepped too close to him, and his rollerbag went over her foot, causing it to wobble. He turned around and glared at her, then picked up the bag and made a motion as if he would throw it at her face. I was alarmed, but then he put the bag down, and I thought maybe they were friends and just joking. That's when he hit her across the face.

There were not many people around, and I immediately stepped between them. He was yelling at her "Why did you do that???" And she was silent, somewhere behind me. I just stood there, and told him to leave.

He walked toward me, and I hit him lightly on the chest to make him step back. It's different in real life - even though I had just seen this guy hit a girl, I didn't want to just drop him. He was a person. So three times he came too close, and three times I hit him lightly to push him back.

Finally, he was annoyed at my hitting him, and grabbed my wrist. Yes, that's right - he grabbed my wrist. If anybody here has ever studied marital arts, the first thing you are taught is what to do when somebody grabs your wrist. I stood there for what seemed like a few seconds (but was probably no time at all), in complete amazement. We had practiced and practiced what to do when somebody grabs your wrist, and I always thought to myself, "This is so stupid. Who is ever going to grab my wrist in a fight?" But here this guy was, in conflict with me, with my wrist in his hand.

I put him in a wrist lock and kicked out his leg so he was on the ground. That's when Mr. Good Samaritan came and stood between us, thinking I had been wailing on this poor soul for no reason. I backed up, Mr. Good Samaritan tended to the downed man who himself tended to his hurt wrist, and I took the girl by the wrist and walked around them both, bringing her to the exit. On her way past, she told Mr. Good Samaritan that the man had hit her, and he apologized to me.

After we got out, I asked if she knew him. She said no. I asked why he had hit her? He didn't seem drunk or anything to me. She said he was just crazy. I said goodbye, and left. I realize I could have asked her out or something, but she was a solid 6 so I just went home.