An elderly couple in a senior's home used to visit the recreation room
   everyday. While
   there, the old lady would sit quite contently holding the old guys's
   penis. One day she goes
   down to the rec. room and is mortified to find her man with another
   women holding his
   penis. "What's she got that I don't have" she says. He looks up with a
   large smile on his
   face and replies "Parkinson's"