My friend first explained sex to me when we were about 8 or so. She explained that men were made up completely of sperm cells, and women of eggs. When they lied flat against each other, the woman could get pregnant from it.
Not only that, she had me worried I was pregnant from horseplaying with the boy down the street.
A childhood belief about reproduction

others believed things like this
- I use to believe that the man peed in the woman to get her pregnant. Didn't know about sperm until sex ed. — das
- a friend of mine thought that you could get pregnant by swallowing sperm. Ha!Anon
- a male friend of mine used to think that only women who had been pregnant had periods— oiman
- I didn't understand about boiled eggs until my Mum explained I wasn't supposed to eat the shell as well.— Chris
- I used to believe that if you ate eggs for breakfast everyday you'd get pregnant...Anon
- I used to believe that women got pregnant just by kissing. — Lisa