An 85 year old man marries a lovely 25 year old woman. Because her new husband is so old the woman decides that on their wedding night they should have separate suites. She is concerned that the old fellow could overexert himself. After the festivities she prepares herself for bed and for the knock on the door she is expecting.

Sure enough the knock comes and there is her groom ready for action. They unite in conjugal union and all goes well whereupon he takes his leave of her and she prepares to go to sleep for the night.
After a few minutes there's a knock on the door and there the old guy is again ready. Somewhat surprised she consents to further coupling which is again successful after which the octogenarian bids her a fond good night and leaves.
She is certainly ready for slumber at this point and is close to sleep for the second time when there is another knock at the door and there he is again fresh as a 25 year old and ready for more.
Once again they do the horizontal boogie. As they're laying in afterglow the young woman says to him, "I am really impressed that a guy your age has enough juice to go for it three times. I've been with guys less than half your age who were only good for one."
The old guy looks puzzled and turns to her and says, "Was I already here?"