If I'm afraid of someone on the street, I'll turn to him (it's always a boy) and say, "Excuse me, do you happen to know what time it is?" This is my way of saying to the person, "I see you as a friend, and there is no need to hurt me or take my stuff. Also, I don't even have a watch and I am probably not worth mugging." So far, it's worked like gangbusters... And I've discovered that most people I'm afraid of are actually very friendly.