I remember being in 5th grade and watching my first "informative" video about puberty. They demonstrated via cartoons what happened when a girl got her period and also what happened when a boy orgasmed [for some reason...I'm guessing they went on to talk about how babies were made but I had probably shut down with embarrassment by then].
Anyway, I had just gotten my period and hated it, so when the narrator was talking about how stuff "ejaculated" from the boys penis, I clearly remember thinking "HA! At least they have to go through something, too!"... as in something unenjoyable and that they didn't enjoy.
They belief continued till I was in 8th grade and foolishly clicked a porn link that was in my inbox. That's when I discovered that they enjoyed it A LOT and "jerking off" a guy was not the cruel practice I had imagined.
Oh, how very young and mistaken I was.
A childhood belief about rude bits

others believed things like this
- In 6th grade, I thought that once you got your period, you'd have it forever!!!! 24/7Anon
- I used to think that dreams were events that really happened, I just couldn't remember them when I was awake.— Warren
- For years I thought that spunk was a male period and that boys spunked once a month - Yeah right!— Stupid Child
- i used to belive life had already happened... i was just watching my judgement— jmsiona
- I used to believe that boys had boy babies, and girls had girl babies.
That was when I was 3-7. I'm 15 now.— Stefanie Michelle - I thought cartoons were real, I remember asking my mom why there were lines around the "actors" in a cartoon.— Steven Graziano