One day Joe complained to his friend, 'My elbow really hurts. I guess I should go to the doctor.'

His friend advised 'Don't do that.

There is a computer at the drugstore that will diagnose anything quicker and cheaper than a doctor.

Just put in a sample of your urine and the computer will diagnose your problem and tell you what to do about it. It only costs $10.'

Joe figured he had nothing to lose, so he filled a jar with urine and deposited the $10.

The computer started making some noises and various lights started flashing.

After a brief pause, out popped a small slip of paper on which ...