Jam,
I am trying to remember to keep a bit of cash on hand at all times when out for just that purpose. Once my wife was approached by a woman panhandling on a subway car. She didn’t have any small denomination cash on hand, so she gave the woman $20. Several months later, my wife was riding the subway again, and the same woman got into the car and started to panhandle. When she saw my wife, she gave her a big smile and did not hold out the cup. She remembered.