A 75-year-old man went to the 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 the previous day.
The doctor asks 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 nothing. Then I asked my wife for help. She tried with her right hand, but nothing. Then with her left, but nothing. She even tried with her mouth, first with her teeth in, then with her teeth out, and still nothing. Hell, 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 that jar opened!"