Since very small boys who are being potty-trained sit down when they pee, I thought that if you couldn't pee standing up then you would stay a toddler forever.
A childhood belief about weeing and pooing

others believed things like this
- if i rolles my eyes, it would stay like that foreverAnon
- I used to believe that bodies that were embalmed would stay preserved forever.— Leelee
- My mom always told me if I made an ugly face it would stay that way forever.Anon
- when I was young I used to believe if I squinted my eyes and it was windy my eyes would stay like this forever— Jeanne
- I used to believe that grown-ups were born "grown up" and that I would stay a little kid forever.— Still A Kid
- I used to believe that boys couldn't be teachers because they weren't smart enough. — Azz