I have spina bifida, which means sometimes I hurt my back in the gym.... nothing really bad, as I'm pretty careful with it but sometimes I get some pain and it's usually pretty bad the next morning.
Back when I was 16 I did squats for the first time and fucked my right knee. That's the last time I let my dad show me how to do an exercise.
Somehow I hurt my neck while doing military presses, and I had to go have physio about that. When doing heavy presses, I naturally tense up all my neck and face muscles.... and something in the back of my neck just went *click* and that was that. Couldn't go back to the gym for about two weeks.
And then there's my elbow, which put an end to my boxing career. Well, wasn't really a career. But I hurt my elbow while sparring and while my coach told me to stay out of the gym and let it heal, I didn't want to lose size or strength.... so there I was doing heavy pulldowns and triceps extensions. Now it's permanently damaged.
None of these have anything to do with warming up or stretching, though.