When I was about 4, I became convinced that if I the toilet was closed and I opened it, I would see the face of my mother's youngest step-brother looking at me. I was terrified and would make my mom open it for me.
I barely knew him, but I suspect I must've had some weird dream that led to that fear. It took about 2 years to get over.
A childhood belief about fear of

others believed things like this
- My brother (who was 6 at the time) would never flush the toilet in fear of our new house being blown up! Anon
- I used to think if I left the toilet seat open my cat would get flushed down the toilet.— G
- That when u opened all the windows on just one side of the car the wind would make it tip over.— Schmackalie
- I used to believe that north was always straight ahead. I could never face south, but I knew it was behind me!— Bruces
- I used to believe that I HAD to make up my own language and teach it to everyone. I was soo weird.— one day maybe!
- my brother told me that if i ride my bike with my mouth open i will swallow my tounge. Anon