As I can recall, only one time someone came to class with a cast on, he blocked a wrench to the head and broke his arm. It was the only injury he suffered while opening up a can of WhupAss on a couple of thugs who were trying to steal his bike. There was also a bunch of LEOs at my school and occasionally one of them would come in with a few scrapes and bruises, they were usually the consequence of a resisted arrest. One time though, my brother and I were horsing around and a lamp fell and broke on my back. The glass had sliced up a flap of skin. My brother wiped off the blood slapped on a band-aid and we headed to class. Half way through training the band-aid fell off the cut opened up and started bleeding profussly, I mean just gushing blood. They quickly ran me to the the changing room where they administered first aid, cleaning and bandaging my wounds. By this time students had begun to arrive for the next class and were horrified when they saw my blood soaked uniform hanging on a hook in the back of the room. "OMG...it finally happened...someone got killed during class". Then the question started, "was there a challenge match?"..."Did a fight break out while sparring?.."Ooo, who died?" They demanded to know all the gory details. Needless to say I was supremely embarrassed to admit the uneventful stupidity that had led to this supposed bloodbath.
Taiji Quan for Self Defense