Yeah, it happenned a few times… :)
The weirdest one was one day, after I went to a gay sex shop. I was biking and wearing my usual blue spandex. So I was unlocking my bike when I see some guy on a wheelchair, mumbling something, and reaching out for my package. I guess he has something like palsy, and I figured out it must have been years since he got sex, so I let him fondle me (we were on the street, during the day) for a while, and then I went my way. I guess this was my good deed for the day…