Motorcycle accident.
Broken collarbone was the worst part. Broken ribs, internal bleeding, and later an infection with high fever that put me on antibiotics for a while were the least of it surprisingly.
The accident itself wasn't so bad due to adrenaline, however having one piece of the collarbone almost puncture my lung, and the other piece pop out of the skin a little at the top was uncomfortable.
The absolute worst part was recovery. The two pieces of collarbone rubbing together constantly, having to lie on my back still to sleep, while resting my arm in the sling on top of broken ribs. Unable to roll in my sleep gave me severe back pain. I basically had little to no sleep for the first 3 months.
Was prescribed painkillers that didn't do much until they upgraded me to tramidol. I didn't react well to it so I could choose between strong pain and no sleep or strong nausia and vomiting with also no sleep.
Painkillers don't take away the sensation of bone rubbing on bone. The memory alone makes me shudder to this day