Further proof that I'm crazy...
When I was a kid, I thought gender was ridiculously, insanely fluid. I honestly believed that if you changed the way your hair was done and wore the opposite sex's clothes, your genitals would spontaneously change and you would actually become a member of the opposite sex.
It didn't help that I was really sheltered, so that I never saw any long-haired men, short-haired women, transgender people, or cross-dressers during my early years. This belief stuck around until I was 6 and my mom got her hair cut short, and I realized her voice wasn't different and she still had all her curves. But I had nightmares the first night after she got that haircut.