When I was a kid, one day the joints in my thumb locked up. My parents said that it would unlock eventually. It stayed locked for a while, longer than it usually did, and I started to grow worried.
It finally unlocked later on that day, and I went to my mother to say that it finally unlocked. I was rather relieved, I told her, as I feared that my thumb might not unlock and it would have to be amputated. My mother thought that was hilarious.