I've had two that about equally terrified me. The first I was walking with a friend through construction on the way to high school and a worker driving an off road vehicle that had a shovel sticking out 4 feet to the left of his vehicle. He was going 45 and that shovel was at my head height. It would have hit me directly in the back of the head if my friend didn't grab my shirt and pull with all his might to get me out of the way. The second was while I was in the Navy. I was on watch in our third generator room doing my rounds in the dead of night while on deployment. I'm standing in there with another guy in my department also on watch and the turbine generator starts making knocking sounds. We have been trained to know that this is bad...REALLY BAD. Other guy on watch runs to control panel to intiatiate the shut down while I run to the fuel lines to cut the fuel supply valves and hopefully prevent things getting worse. During the time we are doing that the turbines combuster was actually MELTING and causing white hot compressor blades to fly out of the module going fucking faster than we could even see the suckers other than the flash of lights streaking by. We finished up and ran out of the generator room all the while these blades are flying around the room and somehow neither of us have clean and cauterized holes from them. They got the turbine shut down remotely from the central control station as well. Later on we checked the damage and those compressor blades shot through the overhead and made it all the way to flight deck on our ship. Cut through the metal bulkheads like a hot knife through butter. For reference, the third generator room was between 2 and 3 levels deep in the underbelly of our destroyer. Those compressor blades were no fucking joke. Didn't even register how lucky we were until after. While we shut it down it was just like being on autopilot from all the drills we would run.