When I was four, I had an imaginary friend. Naturally, it was a purple cow that looked (ironically) like the calf on the milk cartons.
One day, my mother--who was totally unaware of my dealings with THE cow--came and sat down in my room while I was chatting away. I turned around when she said something and was extremely shocked to find that she had sat on my purple cow, and, in effect, had deflated her. You can only imagine how angry I was with my mother.
Things did pan out though. After all, purple cows come back to life, and mine did an hour later.
A childhood belief about imaginary friends

others believed things like this
- When I was little, my dad told me that if you pee in the pool the water will turn purpleAnon
- I used to believe that God was the Incredible Hulk - he was green and muscly and had purple trousers.— Emma
- When I was younger, I used to think that barney was a giant purple and green puppy!Anon
- My big brother told me that if you peed in the pool, it would turn purple and chase you.— Elizabeth
- if you drank coffee before your 16th birthday, your skin will turn purple.Anon
- I used to believe that people's brains differed in colours. I always wanted purple brains for some reason.— Katrina