There was a 40 year old man called Ian, and he had a girlfriend, Edna, who was 80 years old. They only saw each other on Saturdays. He would go to Edna''s house every Saturday, without fail. They would sit down next to each other and Edna would hold Ian''s penis, then Ian would go home after so long.
One week Ian never turned up, but Edna thought nothing of it. Three more weeks went by, and again Ian never turned up. By this time Edna was very concerned about him. She phoned him up and asked, "Where have you been the last four Saturdays?"

Ian replied, "I have been round at Margret''s house."

Shocked Edna shouted, "MARGRET? She is 98 years old, what the hell has she got that I haven''t?"
Ian answered, "Parkinson''s desease!"