"Tennis elbow {sexual content}" joke

A man complained to his friend, "My elbow really hurts. I guess I should see a doctor."
His friend offered, "Don't do that!!! There's a computer at the drug store that can diagnose anything, quicker and cheaper than a doctor. Simply put in a sample of your urine and the computer will diagnose your problem and tell you what you can do about it. It only costs $10.00."
The man figured he had nothing to lose, so he filled a jar with a urine sample and went to the drug store. Finding the computer, he poured in the sample and deposited the $10.00.
The computer started making some noises and the various lights started flashing. After a brief pause, out popped a small slip of paper on which was printed:
You have tennis elbow
Soak your arm in warm water.
Avoid heavy labor
It will be better in two weeks.
Late that evening while thinking how amazing this new technology was and how it would change medical science forever, he began to wonder if this machine could be fooled. He decided to give it a try.
He mixed together some tap water, a stool sample from his dog and urine samples from his wife and daughter. To top it off, he masturbated into the concoction. He went back to the drug store, located the machine, poured in the sample and deposited the $10.00. The machine again made the usual noise and printed out the following analysis:
Your tap water is too hard
Get a water softener
Your dog has worms
Give him vitamins
Your daughter's on drugs
Put her in rehab
Your wife's pregnant
It ain't yours - get a lawyer
And if you don't stop jerking off,
your tennis elbow will never get better.