DS started a new karate club a few months ago. When I first met the instructor he seemed nice, the kids liked him and he had a healthy attendance at the club. I stayed for the first few lessons to watch and the instructor started to concern me a bit after a while. He asked one teenage girl if she was still having bother at school. She said no so the instructor said "good, did you punch them like I said?" and she said yes and he said "excellent!"
He explained to one little lad why his punch was wrong by saying "when you hit someone with this, you wanna make sure the skin on their nose tears on contact so drive it right in, trust me, they wouldn't get back up again".
In another class he went into great detail about some alteration he'd had with another bloke that ended in him knocking the guy unconscious and he actively encouraged one boy to beat up another boy as he was "being cocky".
I don't know if this is normal for a karate class, is it all bravado or what? He seems like a really nice bloke until the class starts, then he turns into a complete physco. But the kids seem to love him.