flybymike, I've heard that one, but it was a slightly different version.
Pilot goes in to see his GP to have his medical signed off. After going over his records, the GP enquires delicately about his current level of sexual activity.
Doctor: "Now, Eric, when did you last have sexual intercourse?"
Eric: "Well, that would have been about Nineteen fifty-two..."
Doctor: (trying not to show astonishment} "That was quite a while ago...."
Eric, (looking at his watch) "Not really. Its only twenty-one fourteen now..."
......this joke, like me, is a relic from the previous century.