An elderly couple is enjoying an anniversary dinner together in a small tavern. The husband leans over and asks his wife, "Do you remember the first time we had sex together over fifty years ago? We went behind this tavern where you leaned against the fence and I made love to you.

"How about taking a stroll round there again and we can do it for old time's sake.

There's a police officer sitting in the next booth listening to all this, and having a chuckle to himself. He thinks, "I've got to see these two old-timers having sex against a fence. So he follows them.

They walk haltingly along, leaning on each other for support, aided by walking sticks. Finally they get to the back of the tavern and make their way to the fence.

Suddenly the old couple erupts into the most furious sex that the watching policeman has ever seen. They are bucking and jumping like eighteen-year-olds. This goes on for about forty minutes!

Finally, they both collapse panting on the ground. The policeman is amazed. I've got to ask him what his secret is.

As the couple pass, he says to them, "That was something else. You must have been having sex for about forty minutes. How do you manage it? You must have had a fantastic life together. Is there some sort of secret?"

The old man says, "Fifty years ago that wasn't an electric fence."