That's called button pushing anime. Or in other words, the people that made the show are laughing AT you, because none of the adults in the show actually WANT to have any inappropriate contact with a minor.
But ask yourself, what would YOU do, if you taught that age level, and one of the obnoxious girls in the class went 'hey teacher' and innocently bent over to pick something up off the floor revealing she was bare assed.
The girl in question in the show is a troubled youth. The teacher is the unlucky doofus that gets to repair the emotional damage she has suffered.
And meanwhile, hysterical Americans can't deal with Japanese animators that simply don't give a shit about their religious convictions, because Japan is a totally different culture.