This one was not believed by me, but by my brother.
When he was in elementary school, he either believed or had been told that bankers had this red button that they could press if there was a robber. The button would eject their seat and have them fly through the roof. He admitted that flying through the roof would not be so useful- but he still said it was present.
A childhood belief about criminals

others believed things like this
- I used to believe that inside each volcano there was a guy who'd press a button to make it erupt.— Jim, UK
- I used to think that babies were made when you press your mums belly button.
Then a baby would fall out— Chris Hyndman - I believed that if you pushed your belly button, your bum would fall off.— Wendy
- I used to believe that a topless bar was like a bar which has no roof on it.Anon
- When I was in elementary school, I believed my heart moved across my chest throughout the day.— Allison
- I use to think church was spelt turch because of the big T on the roof.Anon