A young woman goes to see her doctor. She tells him she's been having pains in her knees.

-- Well, said the doctor, whatever you do on your knees, try doing it on your back.

So she goes home with the doctor's advice. A week later she comes back to the doctor's office.

-- I followed your advice to the letter, but now I'm having problems with my back.

-- Well then, try it on your hands.

So, again, she goes home and follows her doctor's instructions. Surprisingly, she comes back just a few hours later. The docter, in shock, asks:

-- Already having problems with your hands? I have never seen this before!

-- No docter, my hands are alright, she replies. But my husband isn't that flexible!