I and my friends have been approached by people a total of....I think it was five or six times.
One of my friends has lost goods once. Your phone isn't worth your life, but that doesn't mean one should hand everything over to anyone with a little bass in their voice, some are desperate, and some are just inept. It also doesn't help when they have the audacity to try and go into your pockets.
I did find it absolutely hilarious though that one of my friends actually convinced the guy that his phone was broken and useless, and he believed him! His phone was pretty good actually.