I had a square light cover on my overhead light in my room when I was six-ish. When the lights were off and my eyes adjusted, it looked light the square was slowly growing larger (some sort of trick of the eyes..) I thought there was a ghost in the light all cramped up trying to get out, and if he did, he would eat/kill/maim/etc me.
Also, like most children, I believed in monsters in my closet. To this day (many years later) I refuse to sleep with my closet door open. It has to be FIRMLY shut.
A childhood belief about ghosts

others believed things like this
- i used to believe that i really would end up with square eyes if i watched too much tvAnon
- i believed that if you farted too much in a room and you were to light a flame your house would blow up— the nuclear fart
- When i was little i always thought there were little men inside the traffic lights changing the light— Kiley
- I used to be told that if you watched too much TV your eyes would turn square. — Amy
- If you look at a screen too long, your eyes will turn square.Anon
- My parents used to tell me watching television turns your eyes square.— Ruth