Dress/skirt, heels, and make up. You should act more feminine than you're accustomed. I'm sure you've seen girls before... you should have been able to pick up a few things from what you've seen.
If this really is a bet and you'd like to get back at her a little bit, you could pick out an outfit she typically wears, and pretend to act like an over-dramatized version of her. I promise she won't make a bet with this conclusion again.
Az, guys that like to dress up as girls aren't perverts or sissies.
she could make fun of you if you wore a tampon for a day
I'll bet you're a prevert that wants to dress up like a sissy. Go ahead and do it, man. You don't need permission or advice.
Don't forget to shave your legs and under arms! haha
I had the same thing happen to me in high school, don't sweat it. just wear a long dress with gym shorts underneath and some girl shoes. throw in apurse for ***** and giggles with your friends.