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, "You have your choice of Minty's, Patsy's, Marval's or Eccles' - all the same price.
''And how much is that one?'' the alien asked.
''That one is a male's brain, DTC's and it is £500'' the owner explained.
''Why so expensive?'' the alien asked.
The owner answered,''Well, it's hardly been used!''