Note: these all can work great for both girls and guys. But don't use any of them if you aren't pretty confident that they'll say yes.
1. Invite Her in a YouTube Video
Upload a short video to YouTube asking her, "will you go to prom with me?" (To protect her privacy, either use her initials or set the video to "private.") Send her a link to the video in an IM or text message. Or to send her on a real scavenger hunt, combine it with something else on this list and hide instructions for finding the video in something else.
2. Give Her a Stuffed Animal
Tie a ribbon around the neck of a stuffed animal (I love unconventional picks, like this dinosaur), and attach a tag to the ribbon that says, "Will you go to prom with me?" For an extra dose of cheese, coordinate the animal with the message. For instance, how about a horse that says, "Prom with me: yea or neigh?", or a penguin that says, "going to prom with you would be the coolest."
3. Issue a Parking Ticket
Write a note to him and slip it into an old parking ticket envelope (or, if you don't have one, buy a fake one). Then stick it behind his windshield wiper. You can even write something in the note like: "You're in violation of being too awesome." or: "Your fine for being so fine: take me to prom!"
4. Slip It Into a Fortune Cookie
Buy some custom fortune cookies at Greenfire - they'll fill them with a personalized "Will you go to prom with me?" message. Pass her a cookie in the school cafeteria, or even better, take her out for Chinese food and hand her one at the end of the meal.
5. Ask Him in a Foreign Language
Do you share a Spanish class with him? Slip him a note that says: "¿Usted ira a baile de fin de curso conmigo?" If you share a French class together, give him a note that says: "Est-ce que tu viendras au bal de fin d'année avec moi?" And if you're worried that he might be clueless in every language, pick up a translating dictionary and slip your note into that.
6. Sneak It Into a Batch of Cookies
7. Send Her a Bouquet of Flowers
There's no more romantic way to ask a girl to prom than with flowers. Order a bouquet from FTD or TeleFlora and sign the card, "Will you go to prom with me?" If you want to accomplish the same thing for cheaper, buy a bouquet from the supermarket or make one out of flowers from your garden (with your parents' permission, of course).
8. Make Her a Mix CD
9. Go Old-School with a Formal Invitation
Write an invitation in your best calligraphy on a piece of parchment paper, then roll it up and tie it with a velvet ribbon. Slip it into his backpack or locker, or to get even more authentic, enlist one of your friends to act as a messenger. (For tips on calligraphy, take a lesson from Martha Stewart).
10. Just Come Right Out and Ask Him
Okay, it might not be that creative. But if the guy or girl you're asking to prom isn't guaranteed to say "yes," then it's perfectly acceptable to ask the old-fashioned way. After all, if they want to go with you, they'll agree to it no matter how you ask them.