I believed that if you didn't wash yourself right after exercising the sweat would absorb back to your body and make the exercise ineffective.
A childhood belief about bathrooms

others believed things like this
- When I was little I believed little men and little women worked inside my body to make everything work.— Ashley
- When I first heard "The Exorcist," I thought that "The Exorcist" was something about exercising and work out.Anon
- I thought that exorcise and exercise both meant the same thing— Dobby Bob
- I used to think that tampons were meant to absorb women's urine so they wouldn't have to go to the bathroom.— Koyaanisqatsi
- Until about 6 months ago (I'm 21), I believed a bidet was used to wash your feet in.
Eep!— Rebekah - my friend, up untill she was in her early 20s thought that if you drank gatorade you would sweat in colorAnon