First off, I'd like to apologize for my absence. I do this thing where I'm completely invested in something for about a week, and then I'm over it, basically. That's sorta what happened here.
As the title says, this post will be about what to expect on prom night. This mostly has to do with the social part of it.
First off, there seems to be this expectation around prom night as a night where you can get drunk and have sex or whatever. I'd be a huge hypocrite if I were gonna pull the "Don't have sex or do drugs or drink on your prom night!" talk out of my ass... So I'm just gonna say, don't do anything you're gonna seriously regret, or something that'll change your life for the worst.
Obviously, if you plan to have sex on prom night (with your consenting partner, of course), don't be stupid. Make sure you have a condom, and if you're able to, go on birth control. Keep in mind when you're asking/accepting a potential date to prom what your expectations are. If you're going as friends, make sure that it's known between you two that you're going as friends. Otherwise, maybe see how far your relationship develops with your date until prom night and figure out what you're ready for come prom night. Don't fall under the 'sex on prom night' cliche unless you really want to.
Secondly, you're probably thinking of having a non-sober prom night. I'd be a complete hypocrite if I were to forbid you from drinking on prom night. All I have to say on the matter is, don't do anything stupid and be responsible. Do it with people you really trust and you know will take care of you if you decide to drink. Don't drink and drive or wander away from your after party.
I hope this helped out a little, and I hope this post was realistic enough, because I always read about what to expect on prom night and how people are so against drinking and sex.