This isn't mine, but when she was 12, my friend used to believe that a testicle was another word for “tentacle”.
What’s worse was when she asked me on the phone what a testicle really was.
A childhood belief about rude bits

others believed things like this
- When i was younger i thought that the left testicle carried boys and the right testicle carried girls.— Ed
- My friend's sister believed the lyrics to Gazza's "Fog on the Tyne" were "Fog on the dinasaurs mine all mine"— Suzanne
- My friend used to think that oral sex was phone sex!!!— Margaret
- I always thought that my relatives were really tiny, and inside my phone when I talked to them on the phone.Anon
- A friend of mine seemed to think that 100 pence was worth £6.— Richard Davies
- When a friend of mine was little, he used to think that babies came from supermarkets.— Susanna