I just know there's an 'Irish' joke in this somewhere. 
A Irishman was suffering from pains in his knees, so he visited the doctor.
"You're suffering from a disease that we medical experts call "kneeitis", said the doctor. "Take it easy for a month or so and above all don't climb any stairs. That puts a terrible strain on the knees."
A month later the Irishman returned and after a brief examination was found to have recovered completely.
"Can I climb the stairs now Doctor?"
"Certainly," replied the Doctor.
"Thank Heavens," said the ,Irishman "I was getting a bit browned off climbing up the drainpipe every time I wanted to go to the toilet."
