I have an almost mandatory recommendation: Alcohol.
I have a very fond memory of my senior prom and a group of about 30 of us beforehand just getting hammered and going in.
It was a great time...Everyone carefree as hell just having the time of our lives. Just when I thought the night couldnt get any better, "Wish You Were Here" by Incubus came on. As soon as it started I looked over to a couple buddies of mine and we each yelled in unison at the top of our lungs "Fvck yeah!" The three of us climbed up onto some bleachers (it was in our HS gym) and sang the sh!t out of it. Hell, we even attracted a decent crowd cheering us on, even though I'm not sure if they could hear us over the speakers. Now that I think about it, the song was like an anthem for the night. Good times...Good times.
But anyway...Have fun, man.