"Doctors Orders"

A 75 year old man went to his doctor's office to get a sperm count.
The doctor gave the man a jar and said,
"Take this jar home and bring me back a sample tomorrow."
The next day the 75 year old man reappears at the doctor's office and gives him the jar, which is as clean and empty as on the previous day.
The doctor asked what happened and the man explains: "Well, doc, it's like this:
First I tried with my right hand, but nothing.
Then I tried with my left hand, but still nothing.
Then I asked my wife for help. She tried with her right hand, with nothing.
Then her left, but nothing. She even tried with her mouth, first with the teeth in, then with the teeth out, and still nothing.
We even called up the lady next door and she tried with both hands and her mouth too, but nothing."
The doctor was shocked! "You asked your neighbor?" The old man replied, "yep, but no matter what we tried we couldn't get the DARN jar open!"