A pensioner went to the surgery for a sperm count test. The doctor gave him a jar to provide a sample.

Next day, the man returned with the empty jar.

Curious, the doctor asked why.

"Well, first I tried with my right hand, then with my left, nothing. Then, my wife tried with both hands. Still nothing. She even tried with her mouth, but still no joy.

Vera from next door tried with both hands and her mouth too, but still nothing."

The doctor was shocked. "You asked your neighbour?"

"Yes, but not one of us could unscrew the lid!"