An elderly couple are rocking on their front porch.
All of a sudden the old lady reaches over and smacks the old man right out of his rocking chair.
The old man slowly gets up gets back in his rocking chair, after rocking a few minutes more he turns the old woman and asks
“What was that for?”
“For having such a small pecker all these years!” she replies.
The old man rocks for a while longer then reaches out and smacks then old woman, send her and her chair sprawling.
The old woman gingerly gets herself up, rights the chair and sits down.
“What the hell was that for?” she demands.
The old man glares at her and growls, “For knowing the f*cking difference.”