When I was younger and worked out at home, I was able to put together a small weight set thanks to my uncle. He was a super/maintenance man for different apartment buildings so when people would leave any plates or bars behind, he'd bring them to me. I really I loved and miss those rusty plates. Problem was though that overtime I didn't think about either the spring clips being worn out or the same thing happening to the threads on the bars.
I spent a long time with my head up my ass not doing a lot of variety so eventually I started reading more and introducing different exercises, one being a dumbbell pullover. During one set, the clip gave way and all the plates on the one side (I think a 10, 7 1/2, and two 5's) came falling on my face. I was able to turn my head in time so I barely missed a broken nose and having my front teeth knocked out, but did get knocked on the forehead really good, leaving a nasty gash and scar. Lesson learned

Sometimes the equipment at the gym can make me just as nervous.