Break up with her and wait about a week or two to surprise her with an 8 1/2” by 11” poster that says “PROM?” To make it extra special, write “PROM?” in her favorite color.
Take her to an affordable restaurant (your favorite fast food?) and ask her on the car ride there. Don’t ask her while you’re eating or while you’re driving her home; it’s not as surprising.
Call her when she least expects it! During class is a perfect time to call and ask her. You might have to call more than once though.
BACKUP PLAN: If you don’t get a hold of her that way, send her a text or e-mail that says “PROM? :)” and don’t forget the smiley face!
Does she like pizza? If so, this is perfect! Hangout with her Friday night at your place and let her know that you have dinner covered. She will think that you’re making a romantic dinner, but no, you’ve got something better! Wait until about 10:30 (she will be starving by then) and place an order for a large, cheese only pizza. When the pizza arrives, get down on one knee and open the pizza in front her and say, “I know this is cheesy, but will you go to prom with me?” If you want to get really creative, order the pizza with pepperonis and make sure they spell out PROM.