At the age of around six I overhead my mother talking to an older cousin about periods. I could tell this was grown up business from the hushed tones they spoke in. I asked what was a period, and was told rather mystically (or so I remember) that I would know I had grown up when I got an egg with blood in it.
This entirely changed the context of boiled/poached/fried eggs for me. I would become alarmed as soon as I saw one on my dinner plate, and hack it to bits for fear it might contain the blood of my transition to womanhood.
A few years later, classroom gossip revealed that, in fact, I would require pads to cover my nipples from which blood would squirt ferociously during this perplexing and scary monthly occurence.
And they say childhood is the best time of your life.
A childhood belief about periods

others believed things like this
- I used to believe period blood came from the nipples. I thought that was what "padded bras" were for!!Anon
- I thought pads sucked blood from women. It wasn't until later in life that I knew their actual purposeAnon
- when I was young, I heard that blood had iron in it. I thought blood was red because it was rusty.— Hunter
- HA! I used to think when you got your period, you would just pee blood...I wish it was like that...if only.Anon
- I used to believe that salt would dry up all of my blood because my mother told me so.— Charlotte H
- I used to believe that guns shot out blood because everytime somebody shot a gun in a movie you saw blood.Anon