New Testament writers always associated dancing with sexual immorality and drunkeness. We fool ourselves by imagining that alcohol and drugs are not a very dangerous part of the prom scene. Many a young man took his first drink at a prom and many a young girl lost her virginity after a prom. Every year, some youngster gets drunk, high on drugs, and some suffer serious consequences. Chaperones are never able to control the problem.
Dancing incites impurity in thought and action.
Being present at a prom, whether you dance or not, is the wrong thing to do. It puts you in the wrong environment. It doesn't enhance your spirituality. To the contrary, the sexually oriented movements of dancing, the physical contact and handling the bodies of the opposite sex, of necessity excites lust which will lead to sin. If it is right to be present where nothing sinful takes place, it is right to engage in whatever takes place there.