I was visiting a friend of mine in the SF Bay Area, and we were driving off to dinner when we saw two people walking on the opposite side of the street, and ostensibly trying to flag down cars. No one was stopping, so we took a u-turn and pulled up beside them. A woman, clearly relieved that someone had pulled over, says, "Our car just broke down, and I'm late for an interview, and it's really near by -- could you guys please drive me there?!"
She seemed sincere and her story sounded legitimate, so we picked her up. As we were driving, she was mentioning how much she needed this job, and how thankful she was that we had picked her up. She also said, "And I just couldn't believe that no one would stop for us. As we were trying unsuccessfully to flag people down, I was telling my friend that they just don't know what they're missing out on -- they would feel so good for having helped someone in need!"
We dropped her off, and it just so happened to that we had just received a bunch of smile cards from you, and so when we gave her one, she was so excited about it and took 15 more!
As your motto says, Kindness really is contagious!