There are 2 men who are hairdressers. They are the only ones in town. Everyone in town goes to them and never goes to hairdressers out of town. You decide to go to the hairdressers. The one on the left has a big bald patch in the middle of his head. The one on the right's hair is lovely and shiny with no hair out of place. So, which one do you choose, the one on the left, or the one on the right?
The one on the left, the hairdressers have to do each other’s hair.
What can be opened but can't be closed?