How do you feel about donating kidneys?
I think I might be waaaaaay off here, but don't kidneys "grow" back? Kind of like blood, the cells grow back.
Funny thing, I was totally oblivious to taking blood and stuff. One time after getting blood tests I said "mom? What happens to all the blood they just took? Am I going to die of blood loss?". Then she told me blood cells reproduce.
Doh.
Also, after tons of blood transfusions I'm still confused as to why I needed them.