Safety.

Friend is waiting for the subway and some guy tells her she looks good, or something. So she says "Thanks!" and puts on her earphones. Then, the guy starts following her - onto the train, down the length of the car, trying to talk to her, keeping close by. So the next time she sees a cop on the platform, she asks him what she should do if a guy on the subway is harassing her. He says, "I don't know, he probably just wanted to talk to you. I mean, you're pretty good lookin'." So she asks again, and he says, "Well, you could move to the conductor's car, maybe. Or look for a cop. You also gotta carry pepper spray. Every woman in New York should have pepper spray. What's your number - I'll buy you some."