You are in a mall or in an Internet café and a guy in a hurry, looking like a tourist (maybe carrying a bag pack), approaches you frantically. “Sorry to interrupt, I’ve just been robbed and I need your help. Somebody stole my satchel (or purse) and I have all my documents there – passport, ID, cash… From the bottom of my heart, can you please give me 20 dollars for a cab to my hotel, so I can contact my embassy as soon as possible? Please?”
Several people fall for this as the scammer might be very convincing: his speech (having a slight accent as well), gesture, and clothes.
How to avoid: instead of giving him cash, offer to drive him to the hotel or to the embassy, or even let him call using your cell phone. If he refuses, just leave him behind.