I was exiting a boxcar (wagon) with a load of cans (large cans of about 12 gal or so each) in my arms. The door opening was about 10 feet but there was only a 6 ft wide plate in the door way. I put my left foot on the plate and my right foot missed. I exited rapidly sideways and down, spilling the load of cans.
I landed sideways against the edge of the dock, and since my arms were raised because I had been holding the cans, one of my ribs caught the full impact. I had the wind knocked out me, and it was several seconds (seemed like minutes) before I could breath. When finally I could breath, I could barely talk because of the pain and the swelling of my side. This also happened just a few days before the company was to achieve 1 million man-hours without lost time due to an accident - which I put in jeopardy.
My supervisor sent me to the infirmary, where the staff attempted to do an X-ray. Neither the doctor nor the rest of the medical staff apparently knew how to operate the X-ray machine - I got an X-ray after someone read the manual. The doctor determined that there was no broken bones. In the end, I took aspirin and they gave me an ice-pack to keep the swelling down. I went back to work - still in a lot of pain.
A week later, when the swelling finally went down, it was clear that I had fractured a rib, and one can still see the depression on my right side where the rib was broken. I guess I was lucky I didn't puncture my lung.
The company achieved its 1 million man-hours without lost time due to an accident. The next day, a guy was electrocuted and sent to the hospital.

We all got awards for the achievement - I opted for a toster oven.
Then there are the usual, walking or running into doors, smashing fingers with tools, falling off roofs or out of trees, smacking my head into cupboard doors, pipe or structural timber or beams, and a few times as a kid wiping out on a bike or skateboard and hitting the pavement.