How does Alan enact revenge against the people at school who treat him badly?

Alan and Leonard seem to be trapped in the routine of attending a school that cannot or will not meet their intellectual and emotional needs before they have grown into people capable of independent, positive action. Alan therefore amuses them both by tripping the good-looking, well-dressed, snobbish, and ultra-popular kids, the ones who treat them like dirt. When they learn to influence people's thinking with their mental powers, they at first make students, teachers, and the principal do embarrassing things in public such as patting the head and rubbing the tummy for no reason. They also make the principal babble over the intercom like a crazed idiot, and Leonard gives his homeroom teacher a terrible craving for a cigarette and a student an urgent desire to go to the bathroom.

These are all revenge fantasies, bound to appeal to many people besides unhappy young adults, but they are largely negative acts, accomplishing nothing beyond making some annoying people uncomfortable.