An elderly married couple scheduled their annual medical examinations on the same day so they could travel together.

After the examination, the doctor then said to the elderly man: "You appear to be in good health. Do you have any medical concerns that you would like to discuss with me?"

"In fact, I do," said the old man. "After I have sex with my wife the first time, I am usually hot and sweaty, and then, after I have sex with my wife the second time, I'm usually cold and chilly."

After examining the elderly lady, the doctor said, "Everything appears to be fine. Do you have any medical concerns that you would like to discuss with me?"

The lady replied that she had no questions or concerns.

The doctor then asked, "Your husband had an unusual concern. He claims that he is usually hot and sweaty after having sex the first time with you and then cold and chilly after the second time. Do you know why?"

"Oh that old fart!" she replied. "That's because the first time is usually in July and the second time is usually in December."