A man took his pregnant wife to the hospital for delivery. The doctor told them that he invented a machine to split the pain of child birth between the woman and the father of the child. They both agreed to be hooked to the machine.
At first the doctor set the machine at 20%, the wife was feeling better but the husband didn’t feel anything.
Then the doctor set the machine at 50%, the wife was feeling much better but the husband still feels nothing.
Then the doctor set the machine at 100%, the wife was feeling great with no pain but the husband still feels nothing.
When they went home from the hospital, they found the mailman sitting on the doorstep in excruciating pain.