I used to believe that the STOP signs that had "All way" written underneath them meant that you had to come to a complete stop, as opposed the usual way - by rolling through it.
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 believe that the sky had stop lights and road signs floating about for the airplanes.
— LoonaSM's - I used to think that Mice controlled the Stop lights and crosswalk signs.Anon
- I thought if 3 cards stopped at a 3-way stop sign then they had to stop forever until Christmas.Anon
- When I was young, I used to belive that
if you pushed the stop button in the bus it would stop for good.— Tom (Norway) - i used to believe (when i was little) i could make the wind stop and start by saying, "stop" and "start"— Ali