When I was a little girl, my mother told me that my cousin was an "accident." I couldn't figure out how a couple had sex accidentally, so I assumed that while the couple was sleeping, the man's penis could "sniff out" a woman's menstrual blood, and unbeknownst to either partner, engage in sexual intercourse. Thus, my cousin was an "accident."
A childhood belief about reproduction

others believed things like this
- My cousin's mom told my cousin that pop makes you short. He probably believed it.— Molly
- In my second grade class everyone thought that sexual intercourse was "TALKING DIRRTY".— Israel Bliss
- that the word "couple" as in "a couple of items" was synonymous with "several", rather than "just two".— Blair A. Petterson
- I used to think that sex happened on accident while clothed.Anon
- the if you swallowed a fly by accident that you would then grow an appetite for dirt.— sarah
- When I was first told about intercourse, I didn't believe it. How could peeing inside a girl make a baby?— Art