Road signs.
I used to live in a village called Par in Cornwall. Everyday i used to see signs saying
Par 2
Fowey 4
St Austell 7
I used to think that there were 2 Par's, 4 Foweys and 7 St Austell's.
A childhood belief about road signs

others believed things like this
- Having seen enough red octagonal STOP signs in my time, I used to look out for green circular GO signs.— Gary
- I used to beleive that road signs grew out of the ground.— Tiana
- I used to see "End Road Work" signs, and thought they were a sort of protest.— Sebastian
- I used to believe that the sky had stop lights and road signs floating about for the airplanes.
— LoonaSM's - When I was little, I used to believe that deer could only cross the road at the deer crossing signs. — Shellie
- I always though as a kid that "To Let" signs were public conveniences with an I missing. Really.— Col