When about aged two and a half a friend's son seemed to always have his hand down his nappy. One afternoon he came into the room saying, "Mummy mummy, my willy has a bone in it!"
He knew that your arms and legs had bones in them (after breaking his arm) and had worked ot that his willy must have too since it had become stiff!
I thought this was quite good logic!
A childhood belief about rude bits

others believed things like this
- I used to think a female daddy-long-legs was called a "mummy-long-legs".Anon
- i used to belive that my willy would eat me at nightAnon
- I used to belive that my willy was a snake and if i wasnt careful it would bite— eggbert
- Yeah I believed (because my mother had told me) that your 'willy' would fall off if you played with it :D— Doz
- i used to think that my dad got my mom [mummy] from egypt.. when i was like 7— ...
- When I saw my grand mother was very old I used to believe an Egyptian mummy!!!!
— Eomer83