Back when I was a kid, my best buddy's grandfather passed away and left him a couple of guns. Two of which were SxS shotguns, one a 10 ga, and the other an 8 ga. That's right an 8 ga. Well, we being boys and all, we just had to shoot them. Along with the guns were a couple of boxes of brass shell shotgun shells. We decided to take them out in the desert and try them out. My buddy took the 10 ga, and that left me with the 8 ga. These were both exposed hammer guns. He wanted me to go first, so naturally, I loaded both barrels, and cocked both hammers, aimed the gun at a mid sized barrel cactus about 40 yards away, and...
When I pulled the front trigger, the gun "doubled", firing both barrels. The description of being struck by lightning applies good enough. At first, I didn't know what happened, my vision greyed out, and I thought for sure my collar bone was broken. I managed to not drop the gun, which I considered a victory. I was standing there, kind of hunched over, trying to remember where I was, and I got the sensation that it was raining. The ground all the way around us was wet (this was mid-summer desert outside of phoenix-no rain for months). The barrel cactus was almost completely gone, and it was raining pieces of cactus all around.
I managed to look up over at my buddy, and all I could say was, "Your turn!" and hand him the gun.
It never occurred to us to test them first, to see if they were safe to shoot. That was almost 30 years ago, and to this day I don't think either one of those guns has ever been shot again!
Good times.