A very poor man is having horrible pain in his elbow, but has no money to go to the doctor. A friend of his tells him about a machine at the local walmart, where he could go and pour in a sample of his urine, and the machine would tell him exactly what was wrong with him.
In disbelief he goes to Walmart and tries it. He pours a sample of his urine in and the machine spits out a card that reads "You have tennis elbow. Put it in a sling and rest it for 3 weeks and you will be fine."
He is flabbergasted that the machine gave him a response at all, let alone one that makes sense, but he is still skeptical, so he decides he will try to fake the machine out. So he goes home and gets his wife to pee in a cup for him. To really mess the machine up he has his daughter pee in the same cup. Then to really throw it off he jerks off in it as well.
So he takes it to walmart and pours it in, and the machine spits out a card that reads "your wife is cheating on you, your daughter is pregnant, and if you dont stop jerking off, you'll never get rid of that tennis elbow"