I used to think that everyone had a limited amount of words they could use in their life (a limited amount of mouth movements, and a limited amount of sound), and so when you silently mouthed words, you were using up your mouth movements, and so in the end, you'd have extra sound you wouldn't be able to use.
A childhood belief about general

others believed things like this
- I used to believe that I could control the weather... I had limited success— Mark
- I used to believe that we had a finite amount of skin and that I would eventually run out due to pealing.Anon
- My mom used to say that if I said bad words, poop would appear in my mouth— Nina
- When I was a child, I used to know that using cheques you could spend an endless amount of money— lollo
- When I was younger, I thought a serial killer was a person who ate a ridiculous amount of cereal— Aja
- That everyone had the same amount of skin and that short people were fat and tall people were skinny.Anon