Mass Opeth conversion.

played demon of the fall in english once for a music video thing...
teacher almost pooped herself
class started talking

stupid morons
 
Yeah, play when. They'll listen to the first few seconds and think it's really mellow... then watch their faces when it kicks in. :D
 
I once played Bleak for my music class (back then when that subject still existed).

At the beginning of each lesson we had a thing called "musical dream journey" where someone brought a song and played it for the class.

The first time I played Master of Puppets for them, my teacher was not amused. :D
Some months later when I played Bleak, she was pretty scared. But both times she said nothing, because it was a rule that nobody comments openly, but makes comments only for himself in a little book.

Some people seemed to like the clean parts of Bleak, and the clean singing in general.