I used to know someone who, when young, saw his mother naked and asked what her genitals were called. Flustered and embarassed, she replied with the first thing that came into her head and told him it was her "goat" (she doesn't know why). He believed her for several years afterwards and told me he used to be quite shocked whenever he heard the phrase "that really gets my goat".
A childhood belief about rude bits

others believed things like this
- When i was young,my mother told me that she picked me up from the park. i believed it for a few years— Jennifer~
- When we were little my sister thought if you mixed cow’s milk and water you’d get goat’s milkAnon
- I heard a mother in the street tell her young son not to pick his nose...because his head would cave in. — Ruby
- i told my mother that sex was when two people get naked and tell ghost stories.— linds
- In first grade a boy told me that he could see girls naked with his microscope lens. I beleived it for years.— Jeanette
- my mother told me if i ever swallowed chewing gum i'd turn into a pig, i believed this for many years.— stuart hayward