Up until the age of about 11 or so I had only a rough idea of boys' private parts, I knew about penises but had no idea that testicles existed. Therefore when I saw the boys in their trunks at school swimming lessons I thought the bulges in their groins were the effect of rolling up their penises!
A childhood belief about rude bits

others believed things like this
- I used to believe both boys and girls had penises so i thought sex was when they tied them together.Anon
- I used to think that hot dogs were made from boys' penises.— never eating hot dogs again
- When I was about six, I believed that boys had buttons on their penises--one for pee and the other for poop.Anon
- I always thought cats were all girls & dogs were all boys ... I have no idea why.Anon
- I never knew why boys had to lift up the toilet seat...until my friend told me that boys had bad aim.Anon
- i used to believe you could get pregnant from swimming with boys.Anon