I used to believe that the road signs that said "do not drive on shoulder" meant not to drive while leaning your shoulder on the car door.
A childhood belief about road signs

others believed things like this
- I used to call the shoulder of the road, the elbow.Anon
- I thought you were supposed to drive down the center of the road.— Cassiopeia
- I used to think that the shoulder blades were actually "back breasts".— Kdees
- At the age of about 5, I thought that any man carrying a bag/sack over his shoulder was a burglar.— Police officer, Ola.
- When we were younger my sister and I used to think that our shoulder blades were really sprouting wings.— Raven
- I used to believe that the "cruise control" button in cars meant that the car could drive/maneauver itself.— Myriam