Just had to do this too. I was playing this tune on the street. This three hundred pound "Brother" came right up to the keyboard smiling and looking around at the crowd. When I finished he was stunned. Turns out he plays Bass with a few groups around town. He said his dad used to sing this tuned around the house when he was a kid.

Man, if this kind of stuff would happen more often my conscious would bother me for taking pay. I'd just do it for the smiles. I never forget this night a year or three ago CHECH IT OUT:
http://www.youtube.com/watch?v=b1yBPp14BFI