I had a bad trainer in Taekwondo, he seemed to know his stuff but evidently got a little too involved with some of his underage female students. Ended up in prison.
That made me lol...

I loved staring at the loosely dressed girls during training

Then again, I was a horny teen myself, and had no professional responsability
I still remember the name of our kung fu trainer, Master Dang Tieu Diep, Vietnamese fellow (not exactly authentic tibetan monkey-style master), dude is hard as nails though, long story about Vietnam-war tragedies and such
As teens we used to giggle at him having been robbed "not much of a kick-ass mo-fo, eh!" then I grew up and thought dude, anyone can be robbed - then heard it was a home invasion while he was away
NOW, come to think of it - in my service I shared room with a tae kwon do black belt! His girlfriend was ALSO a tae kwon do black belt. He told me he was once walking with his girlfriend, and Trondheim's ONLY mugger - and unluckiest mugger - tried to mug them, with a fucking knife! This shit never happens! Incredible bad luck! This guy is no braggart either, cus I dragged humiliating stories out of him, like how he actually screamed like a woman, and cried, when a small propellar plane he travelled in, was wobbling fiercely during a storm
This guy was attempted mugged, he told the mugger as sincerely as he could "don't do this... you don't want to do this... "
The mugger was baffled, and opted to kick him, instead of stabbing, to which my friend reacted by pure reflex - caught the muggers leg, and karate-chopped the femur in half.
I asked if it made a sound. He said it made a loud, dry clapping noise, and seemed to allready be suffering with the memory. I laughed.
He told me both he and his girlfriend remained with the sobbing mugger, comforted him, and waited for the ambulance with him.