I used to believe that on your birthday, you didn't advance to your next age until you ate your birthday cake.
A childhood belief about birthdays

others believed things like this
- I used to believe that all dessert was birthday cake.— David
- Up until I was almost 11, I thought that a birthday suit was a special outfit you wore only on your birthdayAnon
- I used to think that a birthday suit was a special outfit you wear on your birthday— Bri
- My parents have the same birthday -- month, day, and year. I though all mom's and dad's had the same birthday.— Cait
- I thought you didn't have to go to school when it was your birthday.— M_1
- i used to think that if i didn't celebrate my birthday each year my younger sister would catch up with me— q