I used to believe I had an imaginary friend named (of all things) Diarrhea. And her Dad was the tree outside my Gramma's house and her Mom was the bush at the park by my Gramma's house. My sister used to torment me and say she was going to 'flush' my dear old friend away.
I don't recall how or when or why I outgrew my friend.
A childhood belief about imaginary friends

others believed things like this
- I used to have an imaginary friend named Mr. Nobody. He would protect me from my imaginary enemy, Bad Elmer.— Kdees
- When I was little, my dad had a friend named Scott. I thought my dad's friend was the king of Scotland— Uhhh....
- i used to think my grandmother's actual name was Gramma!— el kristadore!
- My little sister's imaginary friend was Kit the talking car from that show Knight Rider.Anon
- My friend's mom told my friend's little sister thatI when a dog died, it went to a retirement home.— ellen
- When I was six I had an imaginary friend named Binky. When I was seven my dad ran over Binky with the car.— Shadia Granger-Malfoy