I was at a gas station once and someone approached me with a sad story about needing to get somewhere (I don't recall the details) and he was broke, could I give him some money for gas. This is a common scam but he seemed genuine and I was in a good mood. I said I did not have any cash but I would buy him a tank of gas, which I did. Then I went back to fill my own car, and the pump never charged me. I swiped my card, filled the tank, but the charge never appeared on my credit card.