An old man was given a jar and asked to provide a sperm sample for his doctor. The next day he returned with the empty jar and explained,

"Well, doc, it's like this: First I tried with my right hand, then I tried with my left. I asked my wife to help. We even called up Arlene, the lady next door. Nothing." The doctor was shocked. He said, "You asked your neighbour?" "Yep," the old man replied. "None of us could get the jar open."