This is one of the hardest things for adolescents with developmental delays or mental retardation - appropriate sexual behavior.
I'm really very surprised though that his teachers aren't helpful and don't know how to react to impulsive behavior in your son.
Here is a link to the ARC in Milwaukee - I feel sure they will have resources that will help you. This is a VERY common problem among teenagers with developmental disabilities.
Boys in the mainstream population struggle to behave appropriately, and it's doubly harder on boys like your son.
ARE YOU KIDDING ME???
the teacher is not much help? do you know the number of students this teacher has the responsibility of each day? is he 1 of 2, 1 of 5 or 1 of 15?
Currently I have a student who is 100% concentrating on woman's breasts and will cross any barriers to touch them, woman, classmate etc. I have 14 students all with Mh needs, when does the teacher get help? and the teacher have the ability to say I cannot do this?
I think rockrose gave excellent advice to this post that is very old.