Though I live in Seattle, there's an ice cream place on what we call The Ave. Earlier this year, in the afternoon, I went there to grab a bit of something to carry back down to the classroom while I worked on a school project.
When I got there, I ordered, got my ice cream, and forked over a $20, fresh from the ATM. But the cash register was broken. The guy seemed to be new on the job. So he fiddled with it--I didn't mind standing around and waiting; I was hardly in a hurry. But ultimately, he gave up and told me to just go. With my 20.
I assumed it would come out of his pocket. I didn't have change myself. So I left, carried on. It was nice of him.
But my story doesn't end there. I passed by again that night and noticed the place was busy. Which meant the register had been fixed. So I went, had dinner, came back and handed him the 20 again. I had to remind him what it was for.
I still wonder what he thinks of the experience. For me, it was about not feeling (irrationally) guilty, and not letting someone take a hit for me when it was well within my means to prevent that. I don't know if that counts as random or kind, but it's the story that popped into my head when I read the prompt.