I got hit up by a kid needing money to air up his bike tire near campus in Topeka once. Later I passed again and I saw that I had been scammed. When one of his friends asked me the same question, I told him to get some from his friend! HEY OH!
Also, I usually just give out gift cards that I have in wallet or tell them they can have whatever money is in my wallet. Usually a buck or two. Just depends upon how I'm feeling that day.