The wife says to her husband "do you remember when we came here all those years ago?"
"Yes" he relpies "and we went out to the alley way and had sex."
"Yes" she says "do you want to do it again?"
"O.K." he replies so they finish their meal and go out round the back of the diner.
He pushes her against the fence and lifts her skirt up and starts going at it like a wild one. A young man stops to watch. He is amazed to see how the old man can still go for it at his age. After 45 mins they finish and the wife returns to the diner.
The young man says, "How did you keep it goin for 45 minutes at your age? I hope I can do that when I am 80!"
"Well" says the old man, "50 years ago that fence wasn't electrified!"