"Young at Heart" joke

An 80-year old couple decided they wanted to have one more child. The wife suggested they discuss this with their doctor, so they visited with her.

Their doctor first suggested that the man have a sperm count check to see if he had enough ammunition. She gave the old man a jar and said "Take this in that room and provide me with a sperm specimen."

After 30 minutes of grunting, groaning, and screaming behind the door, the old man appeared, obviously disheveled. "Doctor, can I bring my wife in with me?" he asked.

"Sure, whatever helps!" the doctor replied.

The old man's wife entered the room with the old man, and closed the door. Sure enough; another 30 minutes of grunting, groaning and screaming ensued. Then the couple opened the door and stepped out of the room, sweat beading on their foreheads, their clothes wrinkled and obviously frustrated... The old man handed the jar to the doctor.

The doctor took one look at the jar and said, "The jar is empty. Didn't you have any luck?"

The old man replied, "Doctor, I tried with my left hand, I tried with my right, I tried with both hands. My wife tried with her left hand, she tried with her right, she tried with both hands. She tried with her teeth in, she tried with her teeth out. We just couldn't get that lid off the jar."