A childhood belief about weeing and pooing

I grew up on a dairy farm and often saw my uncles moving loads of manure around in wheel barrels to take it to be used as fertilizer for the garden. As a kid I believed that there was a door inside my anus and behind that door there was a tiny man with a wheel barrel full of poo. When the wheel barrel was full of poo the little man would knock on the door, and his knocking would get louder and more urgent the longer I waited. When I really had to go, I would exclaim, "The door's about to BREAK!"