I used to believe that your social security number because your phone number when you grew up - understandable, because the first three digits of my own social security number happened to have been the same as the first three in my phone number! :)
A childhood belief about telephones

others believed things like this
- when i was little i believed that your social security number was the number you were born on the earth — christine
- there's such thing as "soul-security"( social security )
because of the way my stupid parents pronounce it— elizabeth - I used to believe social security ensured you would always have friends— Stephanie Pardi
- I used to believe there was a number "eleventeen". I could never quite work out where it went, though.— Matthew
- I used to think boys went "number two" with their pee pees. Anon
- I used to believe that twenty was the largest number in the universe.— Bernardo Fernandez