My mom is a Labor & Delivery nurse so I always knew where babies came from and that it involved sex. But I distinctly remember thinking (around age 4 or 5) that sex was peeing into the mouth of your significant other. Strange!
A childhood belief about sex

others believed things like this
- I used to believe that Labor Day was when all women had their babies!— Taralyn
- I 'used' to believe that LABOR DAY was when all the pregnant women had their 'labor' pains. lol— melissa in san diego
- I remember drinking red kool aid and peeing at the same time. I was expecting it to be red.Anon
- When I was 7 I used to think that sex was just lying in bed naked next to your significant other— Lou
- I used to believe that babies were born through the mom's mouth.
Don't know how I came up with that. — Makenna - I used to believe that babies came out of their mother's mouth like a small bubble.— Evelyn