An elderly man and his wife visited their GP.

After his exam the doctor said to the elderly man, 'You appear to be in good health. Do you have any medical concerns you would like to ask me about?'

'In fact, I do,' said the old man.

'After I have sex with my wife I am usually hot and sweaty, and then, after I have it with her the second time, I am usually cold and chilly.'

After examining his elderly wife, 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 said to her: 'Your husband had an unusual concern. He claims that he is usually hot and sweaty after having sex with you the first time, and then cold and chilly after the second time. Do you know why?'

'Oh that crazy old fart,' she replied. 'That's because the first time is usually in January and the second time is in July.'