As a kid, I found out I could pull my foreskin back before anybody told me that I could. It could only go back so far.
My childbrain decided that obviously it was the foreskin that was holding my bellend in place, like an eyeball in a socket.
I then became worried that I could pull it back too far, and my bellend would fall out and be left dangling by my urethra.
I realised this wasn't the case pretty quickly, but for a while there it was a definite source of anxiety.