A man with stomach trouble wanted to try the newly introduced automated diagnosis machine at the shopping centre. He inserted his credit card an a urine sample as instructed, waited 30 seconds and then read the printout: You have a tennis elbow.

The man was impressed, but at the same time annoyed as his arms were perfectly alright. He decided really to put the machine to the test, so he went home and collected urine samples from his wife and his cat, and for good measure added the contents of a used condom.

He returned to the machine, inserted his credit card and the combined sample.

After 30 seconds the printout read: Your cat is going to have kittens, your wife is perfectly healthy, but you should quit masturbating when you have a tennis elbow.