A doctor had just delivered twin boys. The head nurse brought them out for their father to see. He could hardly believe his good fortune. The twin boys were each enclosed in a blue blanket and cap. He took one step forward just so he could touch the babies and believe they had finally arrived.
As he started to touch them the nurse took a step backwards and said, "You can't touch those babies. You aren't sterile!" With out missing a beat, he said proudly, "You're telling ME I'm not sterile!"