Red cars cause accidents.
When I was around 5 my older brother told me that red cars are in the most accidents. Obviously, he was quoting something statistical. For years I thought there was something intrinsically dangerous with red cars and was puzzled why people would intentionally purchase something that was known as "more dangerous".
A childhood belief about cars

others believed things like this
- I always thought that freak accidents where accidents that only involved freaks.— Prologic-H-73395
- I thought that people were like cars because cars have exhaust pipes, and people fart.— Matt
- I thought the no overtaking sign meant that red cars cannot drive by black cars.— Helen
- I thought small cars grew up to become big cars— carhugger
- I used to believe that God was the one playing "cars" with our cars. Sounds weird hey?— Roe
- i used to believe people were put in coffins because they were special cars that could drive you to heaven!— jym