It wasn't until I was in my twenties that I learned this was called Precordial catch syndrome and it happens to most everyone. Every friend I've told about it was surprised, and also most knew the feeling.
I collected a growing list of strange things bodies do ever since. And now finally I made it into a little page for others to see:
https://vester.si/bodily-oddities/
It includes a form to tell me about new things, if you think they belong on the page. Feedback welcome!
Show HN: Bodily Oddities
vester.si