At 85 years of age, Morris married Lou Anne, a lovely 25 year old.
Since her new husband is so old, Lou Anne decides that after their wedding she and Morris should have separate bedrooms, because she is concerned that her new but aged husband may overexert himself if they spend the entire night together.
After the wedding festivities Lou Anne prepares herself for bed and the expected "knock" on the door. Sure enough the knock comes, the door opens and there is Morris, her 85 year old groom, ready for action. They unite as one. All goes well, Morris takes leave of his bride, and she prepares to go to sleep.
After a few minutes, Lou Anne hears another knock on her bedroom door, and it's Morris. Again he is ready for more "action". Somewhat surprised, Lou Anne consents for more coupling. When the newlyweds are done, Morris kisses his bride, bids her a fond goodnight and leaves.
She is set to go to sleep again, but, aha you guessed it - Morris is back again, rapping on the door, and is as fresh as a 25-year-old, ready for more "action". And, once again they enjoy each other.
But as Morris gets set to leave again, his young bride says to him, "I am thoroughly impressed that at your age you can perform so well and so often. I have been with guys less than a third of your age who were only good once. You are truly a great lover, Morris."
Morris, somewhat embarrassed, turns to Lou Anne and says: "You mean I was here already?"
*The moral of the story: Don't be afraid of getting old, Alzheimer's has it's advantages.*