Here are my top 3.

Story 1. Crashed on the local BMX track, going flat out down the start hill (and as a retired racer I was able to get good speed), foot slipped on peddle at the bottom of the start hill at the first jump. I did an epic superman, I had grazed my shoulders, elbows, ribs, knees and hip - badly, I could see my own hip bone. When I arrived at A&E I needed a lot of cleaning up, with a scrubbing brush, to get the grit out. Even with full dose of painkiller, I was wriggling and writhing with the pain of them scrubbing the wounds to get the grit out.
I spent 6 weeks in a large amount of bandages. 20 years later I still have the scars.

Story 2. Crashed my mountain bike when I was a teenager, hit a wall, compound fractured my wrist.
Was an hour from civilisation, luckily I was with my brother and his friend and we had travelled by car and were close to returning to the car, so my brothers friend rushed back to the car and took us to the nearest hospital.
I can't remember why, but was put straight in a bed and into surgery, no sitting in the waiting room.
First thing they did where they had to inject something (painkiller, anaesthetic I guess) into my bone right were the fracture was, but they had to really push hard, I am talking put body weight on the needle to get it in, it took 3 people to hold my arm still/down whilst they did. That was needed so that they could do some traction on my wrist, 2 people pulling my hand, 2 people on my elbow and someone fiddling with the broken bits of bone to straighten them. Even sedated I managed to put up quite a fight.

Story 3.
Some years later I had another big accident and managed to properly dislocate my hand, break my scaphiod and did major ligament damage. Had to have 4 hours of surgery under general anaesthetic, 3 pins inserted, reattach ligaments. Woke up in agony, even heavily sedated, my arm felt like it weighed 3 tonnes, I could feel the pins in my hand, I stayed in hospital in my own room for 2 weeks, spending a full week on a morphine drip.
I had to have another operation 3 months later to remove the pins, I was only in for 24 hours and the pain was much less.