A husband leans over to his wife in a bar and says, "Do you remember the first time we had sex together over 50 years ago? We went behind this very tavern where you leaned against the back fence and I made love to you."

"Yes," she says. "I remember it well."

"OK," he says, "How about taking a stroll around there again and we can do it for old time's sake?"

"Oh Charlie, you old devil, that sounds like a crazy, but very good, idea!" she says.

There's a man 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. I'll just keep an eye on them so there's no trouble.

So he follows them behind the tavern. The old lady lifts her skirt and the old man drops his trousers. As she leans against the fence, the old man moves in. Suddenly, they erupt into the most furious sex that the man has ever seen. This goes on for about 40 minutes. Finally, they both collapse panting on the ground.

The man is amazed. After about half an hour of lying on the ground recovering, the old couple struggle to their feet and put their clothes back on. As the couple passes the man, he says to them, "Excuse me, but that was something else. You must've had a fantastic sex life together. Is there some sort of secret to this?"

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