An old guy goes to his doctor for his physical and gets sent to the urologist as a precaution. When he gets there, he discovers the Urologist is a very pretty female doctor. The female doctor says, "I'm going to check your prostate today, but this new procedure is a little different from what you are probably used to. I want you to lie on your right side, bend your knees, then while I check your prostate, take a deep breath and say, '99'.
The old guy obeys and says,"99".The doctor says, "Great". Now turn over on your left side and again, while I repeat the check, take a deep breath and say, '99".Again, the old guy says, '99'."
The doctor said, "Very good". Now then, I want you to lie on your back with your knees raised slightly. I'm going to check your prostate with this hand, and with the other hand I'm going to hold on to your penis to keep it out of the way. Now take a deep breath and say, '99'.
The old guy begins,
You don't stop laughing because you grow old.
You grow old because you stop laughing!!