I thought that a "birthmark " was really called a "birdmark" and if a bird pooed on you when you were a baby, It stained the skin and wouldn't wash off.....
A childhood belief about skin

others believed things like this
- Untill I was about 15 I thought that the birthmark on Mikael Gorbachov's head was actually a map of the world.— Rob , Solihull
- In 'Call Me Maybe', I misheard 'Ripped jeans skin' as 'Rich cheese skin'. — Carly Rae Cheddar
- I thought bathing suits were called "baby suits".— Katie
- when i was little, i thought that you could pull your eyeballs and wash them in your mouth— beak
- I once for some reason thought a Mantis was a bird, instead of a bug...— Laurie J.
- I thought birds grew from bird seed. — Jen