I thought everyone had a penis but mine was really small so I couldn't see it (this belief stemmed from walking in on my babysitter's son peeing when we were about three).
A childhood belief about rude bits

others believed things like this
- I belived what when i was peeing, a jellymonster would come out of my penis to punish me.— Shuyin
- I used to believe that a boy's penis came out of his bellybutton, so you couldn't see it all the time.Anon
- i used to think the song "walking in a winter wonderland" was "walking in a womens underwear"— stephen s
- I used to believe that jay walking was walking naked on the street. — Kendra
- When I was younger I thought men had two penises, one for peeing and one for having sex.Anon
- My friend's sister believed the lyrics to Gazza's "Fog on the Tyne" were "Fog on the dinasaurs mine all mine"— Suzanne