45 years of bad sex

An old man and an old woman are relaxing one day on their porch, in their rocking chairs. All at once the old woman reaches over and hits the old man, knocking him out of his chair. He asked her "What the hell was that for?" She replied, "That's for 45 years of bad sex!" The old man climbed back into his chair and began to ponder what had just happened. After about 15 minutes the old man reaches over and belts the old woman hard enough to knock her completely off the porch. "What the hell was that for?" she screamed. He answered "That's for knowing the difference!"