I used to believe people said "Happy New Year with Leaves" instead of "Happy New Years Eve." My family still reminds me of it over 30 years later. Every year.
A childhood belief about speaking

others believed things like this
- Abba - Happy New Year
"Kangaroo year,
Kangaroo year..."— Santa Puncher - I used to believe that people born on leap year would only age once every 4 yearsAnon
- I thought that 1983 went on for 3 years - had to ask my sister who decided how long a year lasted.— Sally
- When I was 5 years old, I used to believe Poland was snowy and cold all year round, like the North Pole. — Sara
- I thought the holiday was called "Merrychristmas" so I would tell people "happy merrychristmas"Anon
- That a dog humping someone's leg was just really happy. — Ruben