I walked into the trailing edge of horizontal stabiliser of the SK76 helicopter I was about to use for a Class A night casevac. The dispersal was unlit and I just didn't realise I was so close to it. The sharp edge caught me right on the side of my eye socket and was excruciatingly painful but did no permanent damage.
But the most painful thing was pulling a heavy GPU over my own toe. It had metal wheels and weighed about 500 pounds. My toe was crushed and the pressure that developed inside it pushed off the toenail after a few days.