I used to believe that the road signs with an arrow pointing UP (as in up ahead) were actually pointing up to the sky. I wondered for many years how people were able to drive up into the sky!
A childhood belief about road signs

others believed things like this
- Street signs with the upward pointing arrow was for airplanes. — Tammy
- I used to believe that a half moon was gods finger nail, and his finger was pointing downwards.— clo
- 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 - I thought you were supposed to drive down the center of the road.— Cassiopeia