A man, about 80, goes to his doctor for a checkup because he is planning to get married.

After congratulations and a clean bill of health, the doctor asks about his fiancée. The old man shows him a photo of a very beautiful, mid-twenties young lady.

Thinking his patient might not be able to keep up with the physical stress of married life, he says, "I think you should consider getting a paying guest to keep your wife company while you have your regular naps." The patient agrees.

Months later, the doctor bumps into the old man and asks, "How is married life?"

The patient says, "Congratulate me, doctor. My wife is pregnant."

The doctor congratulates him, and asks, "And did you take my advice about the paying guest?"

"I certainly did, doctor. Thank you for that advice."

"I see it worked out then," said the doctor, trying hard to hide his smile.

"Oh yes, it did. She's pregnant too."