I crashed my motorcycle back in '85 and damaged a testicle. But it was the least of my troubles as I also had multiple abdominal ruptures. I was lucky enough to be taken to hospital in the nick of time where they opened me up to sort out the mess. They had to chuck away my spleen and one of my kidneys and sew up the other kidney plus fix dozens of other bleeders (they had to give me 20 units of blood during the 6.5 hr op.) The damaged testicle wasn't really noticed until several days later by which time the bruising had spread throughout my scrotum and one side of my lower abdomen. It was still low priority in the scheme of things as I was on life support in intensive care for the first few days. When I was allowed home and had recovered some of my strength I tried masturbating to relieve some of the pent-up sexual frustration. To my horror my orgasm was very painful and the semen came out dark red/brown because it contained so much blood. Yeuch! Bit by bit over the next fortnight my ejaculations cleared and my semen resumed it's normal colour. I don't remember much testicular pain because I was in so much pain generally, but my testicles or at least one of them had been badly smashed between the petrol tank of the bike and my pubic bone (the top/rear of the tank was flattened). I still don't know if both of my balls work, but one of them must because I went on to father a son.