When I was about 11 years old, my best friend and I were playing during recess at school, and I was carrying him around on my back, presumably pretending to be a multipart attack robot. All of a sudden, my heart started hurting, and I collapsed to my knees, and the robot was no more. Every time I inhaled, it would feel like a spike was being driven into my heart, and my breathing got completely shallow. I was sure I was done for, when all of a sudden, after an exhale, it disappeared.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!