An old married couple are rocking on the front porch.

Suddenly, the old woman smacks her cane across the old man’s lap. He says, “What the hell was that for?” She says, “That’s for 56 years of terrible sex!” They get back to rocking. Suddenly, the old man raises his cane and smacks the old woman across the lap. She yells “What the hell was that for?” He says, “That’s for knowing the difference.”