I used to believe that the arrows on the road for going straight ahead actually meant up. I spend much of the time in the car looking for cars flying up and wondering why ours didn't fly!
A childhood belief about road signs

others believed things like this
- I used to believe that north was always straight ahead. I could never face south, but I knew it was behind me!— Bruces
- i used to think technology was "flying cars" and that we would have them by the year 2000.— josieg
- I thought the no overtaking sign meant that red cars cannot drive by black cars.— Helen
- I used to believe that the inspection stickers on cars indicated the cost of the car, ie, a 12 meant $12 etc.Anon
- I used to believe that the "cruise control" button in cars meant that the car could drive/maneauver itself.— Myriam
- i used to believe that the green arrows on the traffic lights told you which way you had to go to get home.— Helen