A 92-year-old man
A 92-year-old man moved into a retirement home where he immediately met a 90 year old woman. They hit it off right away.
After a few weeks of spending time together, the man said, "You know, we're past our sexual years, so I wonder if it would be okay for you to just hold my penis in your hand."
The woman seemed surprised, but said, "Well, I guess it wouldn't do any harm to just hold it." So, for the next few weeks, they could always be found on a park bench near a lake, the lady holding the man's penis in her hand.
One day the old man didn't show up. Beginning to worry, the lady set out in search of him. A few blocks away, sitting on another park bench was the old man...with another woman.
The first old lady approached the couple and saw the other woman holding the man's penis in her hand. She became very upset and yelled to the man, "I thought we had something special. Now, I find you with another woman, and she's holding your penis in her hand. What does she have that I don't have???"
The old man looked up, smiled, and said..."Parkinson's."