An alien walked into a shop and told the owner that he came from Mars and wanted to buy a brain for research.
''How much is this one?'' he asked. ''That one is a monkey brain, and it's $20,'' the owner explained.
''How much is that one?'' the alien asked. "That one is a female brain, and it's $100,'' the owner replied.
''And how much is that one?'' the alien asked. ''That one is a male's brain and it is $500'' the owner explained.
''Why so expensive?'' the alien asked. The owner answered,''Well, it's hardly been used!''