I used to think Cockneys only ever talked in rhyming slang.
A childhood belief about speaking

others believed things like this
- "Chassis" is slang for a woman's body, especially her genitalia.
— Siddharth Mehrotra - For whatever reason, I thought that grass was slang for tobacco rather than marijuana.Anon
- i used to think when my parents talked that "so and so" was actually a person.— karmely cullen
- When I was little I used to believe that dogs talked to each other when barking.Anon
- I used to believe that when we went to bed at night, all the animals in our house talked to each other. Anon
- I used to believe that the more you talked, the sooner you would die. Needless to say, I was a quiet kid.— Lisa