Alright I've never broken a bone, but I accidently broke my sister's. I remember it quite well for some reason. We were both little, I'd say I was around 4 or 5, and my sister was probably 3.
Our family was at the dining table having dinner, and Me and my sister were jumping on the bed in our room (how original). We were having fun, but my little brain had the absolutely wonderful idea of jumping off the wood at the foot of our bed. (the 'bed rail' or fence thingy or whatever it's called.)
So I started standing on it, then jumping on the mattress. I encourged my little sister to do so as well, saying it would be fun. She obeyed, being a mindless 3 year old. I held out my arm to help her get up, and she held it climbing on the rail.
I pulled my arm away, and stood on the mattress waiting for her to jump, and as I did, she fell over. I don't remember this part too well, but all I know is: she fell, and (thankfully) had her arm to break the fall.
She screamed so loudly .. our parents burst into the room. By then, I was burning with horror and guilt. And when they asked what's wrong, I blurted out, "She jumped off the bed rail!" like it was her fault.
.,.
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Anyway ... fast forward a week later and me and my grandmother were sitting in the Veranda (front porch). She showed me a picture of the X-ray. I was shocked, and said, "That's her bones?" Since I had never seen such technology. It was practically magic for me back then.
So yeah ... I remember when I was telling the story to her when we were around 10. She was astonished and went straight to our mother to get me in trouble ... :'3