Prom? Didn't go. No one there I wanted to see. My friends either thought the prom was stupid, or didn't graduate, or otherwise weren't available. And my prom had some extra "but it's tradition" bolted-on retardation where everyone marched slowly around the auditorium for half an hour so everyone else could get a good look at your tux/dress. Like being in line at the DMV, only your clothes are more expensive. Stupid traditions, showing off, and having to act just so for the school's overlords. Most of the things I hated about school, distilled into 30 minutes of pure suck.
So, to summarize: Didn't go. No regrets. Still none over a decade later.
But the fact is, the posts in this thread - mine included - mostly boil down to a few basic archetypes.
1) "I did what I wanted to and liked it. You should do what I did."
2) "I wanted to do this but someone made me do that. You shouldn't do what I had to."
3) "Do something that'll probably get you killed, LOL internet advice."
4) The (rare) inversion of 1 or 2.
My advice? Ignore our advice. Do what you want to do, don't leave a body count or insurance claim, and let everyone else go rot. You might regret it, but probably won't. And if you do regret it, well, that's nothing. Welcome to the human race.