This is probably common but I will tell my tale. When my brother said a classmate of his wore panty hose one day I imagined someone wearing a garden hose for pants. I don't think my brother bothered to correct me.
A childhood belief about appearance

others believed things like this
- I use to believe that people who wore tuxedos were actually wearing the skins of Penguins. — Keith
- I used to belief that the Muslim women who wore their garment wore it because they were bald.Anon
- Not me but my classmate. He thought that stereotyping was listening to the stereo.Anon
- i used 2 think if u lied your pants would catch on fire cus of the sayin "lier lier pants on fire!"— nell
- I used to think that when I was as old as my big brother, I would be a boy too. :)Anon
- My brother used to believe when our dog was getting fat that she was going to pop. He Cried!— A very Ashamed Brother