A young dog had an accident and needed a brain transplant. The veterinarian told the dog's human family, "Brains are very expensive, and you will have to pay the cost yourselves." "Well, how much does a brain cost?" asked the family. "For a male brain, $500,000. For a female brain, $200,000," replied the vet. All the men in the family nodded because they thought they understood. But the mother was unsatisfied and asked, "Why the difference in price between male and female brains?" "Standard pricing practice," said the vet. "The female brains have to be marked down because they’ve actually been used!".