I used to believe...that airbags we literally bags of air that came out in car crashes so that if the drivers were in a crushed/mangeled car, they could still breather (with the air from the bags.) Made sense at the time.
A childhood belief about cars

others believed things like this
- I thought brown paper grocery bags would fit more than plastic grocery bags.Anon
- I used to believe as a child that t-storms (aka thunderstorms) where actually tea bags falling from the sky.— Samantha
- when i was a child (of course)i used to believe that the sea is salty because God throws bags of salt into it.— Kafka
- i believe in the tooth fairy so much that i make paper bags for her!— Monster High girl
- I used to believe that there was a shop in switzerland that sold bags of bogeys with sugar for eating— laura
- I used to believe that cow udders were hollow bags full of milk.Yet I knew that human boobs were solidAnon