I used to think that sex was accomplished with both partners standing up. The couple would face each other, press their privates together, arch their backs so that they are both bending backwards, and raise their hands into the air. And while they are doing this, they would say "Quaaaaah! Quaaaaah!"
Where did I get this bizarre idea? Thinking back, I realize that it came from a poster I saw once in the London Underground, possibly advertising a movie or a dance production, and a friend who was with me told me it was a picture of two people having sex. The "Quaaaah!" was simply a corruption of the British slang "Cor!" which means something like "Oh god!"
A childhood belief about sex

others believed things like this
- When I was little I thought the london underground was a terrorist organisationAnon
- I used to beleive that in order to rewind a film the actors would have to re-act the whole movie backwards. — movies backward
- I used to believe evrybody's privates were diffrent-- thus the name "privates"Anon
- I believed that everytime I kissed my David Cassidy poster he'd feel it back home in Hollywood.— Marie M
- I used to think that fire trucks and ambulances drove all the way back to the station backwards.— Tim
- My younger sibling thought that Brittany was the name of the country where British people livedAnon