When I was 3 or 4, my oldest sister's fiance came to visit for a weekend, and upon waking up one morning I found him washing his hair in the kitchen sink. I was horrified and I began freaking out and pleading with him not to wash his hair in the kitchen sink! I didn't want to tell anyone that the reason was that nobody was supposed to wash their hair anywhere but the bathtub - he was a grownup, and he was supposed to already know this stuff! I still get teased about that to this day.
A childhood belief about bathrooms

others believed things like this
- My mom told me that if I didn't wash my hair black widow spiders would come live in it.— grew up in Nebraska
- I used to think that bleaching your hair meant washing your hair with toilet bleach.Anon
- I use to believe that your hair grew because you wash i.e like watering a plant — HJON
- I was told that if i didnt wash my hair regularly it would turn green— Mimi Screami
- My friend convinced me that if I used a bar of soap to wash my hair instead of shampoo that I would go bald.— Michelle
- I used to think that everybody's hair was black and if you had blond hair, you dyed your hair.— ~_~CoolKid93_~_