I Need Help ASAP... Guys Are Aggravating.

Let me set up the situation.

I have been crushing on a guy (let`s say John) for about 3 months, I want to go to Prom with him but he never asked me.

Everyone in our Limo had a date except me, so my friend (let`s say David) asks me to Prom YESTERDAY. He is very very very excited about buying his stuff and going in the limo and being with me.

Today after 4 MONTHS - John (the guy I really want) asks me to Prom. Unfortunately I found a date (we`re going as friends) the day before he asked.

John is shy and has trouble with asking questions like this so it was really brave of him today.

Quite honestly I don`t want to go with David, I need to make calls TONIGHT! Any ideas about what to do here? Who should I let down? Any clever ways I can have fun with one before and one after prom (just kidding)?

Let me know guys, you all are ever so cool.