What is the title of this movie?

The movie is from the 70's or 80's. It is about teen girls who got to this academy. I thought it was The Von Popsin Academy. But evidently that is not right. The girls end up messing with each other. They get Prairie oysters and road apples (bull balls and horse s**t). One ends up in a porta potty upside down. They put itching powder in the girls undergarments. When they are in class the teacher tells them to sit up straight and tighten the buttocks. And when the do they all fart.