I never knew it was possible to donate a kidney to a stranger. Was reading an article about someone who couldn't find a donor and a commenter mentioned that this was a thing. I signed up immediately.

I'm healthy, I only need one, and like I said, I figure by the time I actually need one we'll be able to grow one -- but I suspect it won't actually come to that.

In that light, it doesn't seem all that altruistic.