A husband leans over and asks his wife

 

the old couple struggle to their feet and put their clothes back on.
The policeman, is still watching and thinks to himself, this is truly amazing, I’ve got to ask them what their secret is
So, as the couple passes, he says to them, “Excuse me, but that was something else.
You must’ve had a fantastic s*x life together. Is there some sort of secret to this?
Shaking, the old man is barely able to reply,
“Fifty years ago that wasn’t an electric fence.