"Labor Pain" joke

A married couple went to he hospital to have their baby
delivered. Upon their arrival, the doctor said he had invented a new
machine that would transfer a portion of the mother's labor pain to
the father.
He asked if they were willing to try it out. They were both very much
in favor of it. The doctor set the pain transfer dial to 10% for
starters, explaining that even 10% was probably more pain than the
father had ever experienced before.
But as the labor progressed, the husband felt fine and asked the
doctor to go ahead and bump it up a notch. The doctor then
adjusted the machine to 20% pain transfer. The husband was still
feeling fine. The doctor checked the husband's blood pressure and was
amazed at how well he was doing.
At this point they decided to try for 50%.
The husband continued to feel quite well. Since it was obviously
helping out his wife considerably, the husband encouraged the doctor
to transfer ALL the pain to him. The wife delivered a healthy baby
with virtually no pain.
She and her husband were ecstatic. When they got home, the
mailman was dead on their porch.