When I was 5 years old my older sister convinced me of the following:
If a girl goes swimming, then a fish (usually a trout) would swim up your leg, lay its eggs in you, & this would result in pregnancy.
Needless to say, I was very frightened to go swimming in our creek for a pretty long time, for fear of getting pregnant!
Older sisters can be so very cruel!
A childhood belief about getting pregnant

others believed things like this
- when I was a child I thougt taht sea waves are the result of whales swimming— waleed bokhari
- i used to believe you could get pregnant from swimming with boys.Anon
- I used to believe that if you went swimming after you got your first period, then you could get pregnant. — Mel
- I used to think that when you swimming 'Freestyle' was swimming any way you want.Anon
- My older sister had me convinced that noodles grew on trees, but that rice was man-made...— Trusting little brother
- a friend of my little sister's had 4 older brothers, so she thought that when you got older you grew a penis!Anon