One day, leaning on the bar, Jack says to Mike "My elbow hurts like hell. I suppose I'd better see a Doctor!". "Listen, don't waste your time down at the surgery," Mike replies. "There's a new diagnostic computer at Tesco Pharmacy. Just give it a urine sample and the computer will tell you what's wrong, and what to do about it. It takes ten seconds and only costs five quid.....a lot quicker and better than a doctor and you get Club card points." So Jack collects a urine sample in a small jar and takes it to Tesco. He deposits five pounds and the computer lights up and asks for the urine sample. He pours the sample into the slot and waits. Ten seconds later, the computer ejects a printout: "You have tennis elbow. Soak your arm in warm water and avoid heavy activity. It will improve in two weeks." That evening while thinking how amazing this new technology was, Jack began wondering if the computer could be fooled. He mixed some tap water, a stool sample from his dog, urine samples from his wife and daughter and the cat, and masturbated into the mixture for good measure. Jack hurried back to Tesco, eager to check what would happen. He deposited five pounds, poured in his concoction, and awaited the results. The computer printed the following: 1) Your tap water is too hard. Get a water softener. 2) Your cat's having kittens. Get a vet. 3) Your dog has ringworm. Bathe him with anti-fungal shampoo. 4) Your daughter has a cocaine habit. Get her into rehab. 5) Your wife is pregnant. Twins. They aren't yours. Get a lawyer. 6) And if you don't stop playing with yourself, your elbow will never get better.