It's simple: post pictures of yourself dressed up as the opposite gender! It also helps to post your original self with it, but that can be optional.
Girl me:
http://img17.imageshack.us/img17/184/kc1mk.jpg
Back when I had long hair...
Boy me:
http://img195.imageshack.us/img195/9240/drag1.jpg
http://img812.imageshack.us/img812/7186/drag2.jpg
Now knock yourselves out!