When I was younger, my mum told me that because it was a leap year, I would miss my birthday and would have to stay the same age for another year. Even though my birthday is in September and nothing to do with leap years, I believed her and cried for ages.
A childhood belief about birthdays

others believed things like this
- I used to believe that people born on leap year would only age once every 4 yearsAnon
- My parents have the same birthday -- month, day, and year. I though all mom's and dad's had the same birthday.— Cait
- i used to think that if i didn't celebrate my birthday each year my younger sister would catch up with me— q
- iwas told that if u cry on your birthday you would not get any bigger 4 a whole year— steve
- My birthday was on a different day every year, assigned by my parentsAnon
- I used to think that your birthday changed every year, and that your parents just decided what day it was.— Daniel