When I was turning 11 I had a backwards birthday party. It was where you and all your guests have to dress up as the opposite sex. So in other words the boys had to dress up as girls and girls had to dress up as boys. Even the adults have to do it. My friends and I all got a kick seeing my step dad in a dress with makeup. For girls to dress up as a boy all you need are some boy jeans and a t-shirt. If you don't have any boy clothes you can go to a thrift store and get some for like two to five bucks. Then what's really cool is you can make the girls have a beard that looks like it hasn't been shaved in two days. You do this by putting corn syrup where ever you want it to look like you have a beard then you put ground coffee where you put the syrup and brush of the excess coffee that sticks to your face and wola you have a beard. For the boys to look like a girl you just drees them up in a dress, makeup, and a wig if you have one if you don't just put pretty girly clips in and don't forget the high heels. If you don't have any girl clothes you can go to a thrift store too. Make sure you tell every one about it in the invitations so they can dress up at home then come to the party. My friends and I got a kick out of seeing all the boys dressed up as girls and I hope your friends will to.