My grandmother was fond of proverbs and would often say "you know what they say..." or "they say that..." When I was little I came to the conclusion that "they" were a group of people in an offfice somewhere, whose job was to sit around all day coming up with sayings and proverbs.
A childhood belief about speaking

others believed things like this
- I used to think being engaged meant being in jail. I have no idea how I came to that conclusion.— CNB
- When I was a little kid i thought cattle meant a group of cats— It's a group of cows and bulls!
- My cousin used to think that a group of nine singers was called a "niner".Anon
- I believed that wind was caused because the trees moved. I was completely sure my conclusion was correct.— Glenr
- i used to think that the paparazzi were a group of Italian criminals or spies. i have no idea why?? Anon
- When I was four I saw a group of nuns and told my grandma...look there's a bunch of brides with raincoats on.Anon