Strange ways of this city!

This incident happened to one of my friend here in Bangalore yesterday. I want you people to know about this because i never thought some one will come up with such a noble excuse and do a bad thing to a unsuspecting human. Well, the story goes like this. My friend is walking to his place after he gets down from the office transport after the day's work. A normal looking guy comes in a motor bike and stops by my friend. He asks my friend if he could borrow my friend's phone to make a call to a person he knows who has met with an accident and needs help. Naturally if someone comes with a request like this what would a normal guy do is unsuspectingly help the stranger as it might be a emergency situation. Now once my friend has passed this Mr.Stranger his cell phone to make this supposedly urgent call, he promptly takes it and speeds away!!! wtf! My friend is shocked and before he knows what is happening, he has lost his cell! I wonder if you guys have come across such an experience ever but this was something new to me. I've heard people snatching the cell phones away from pedestrians or from people's hands and neatly running away. But coming and making up some genuine looking reason and then fleeing with the phone is something new to me! Now, the question is how to ever trust someone on the street? I'm not sure I'll ever trust people easily henceforth from now on.