A concerned woman phones a doctor and says, "Doctor, I'm worried about my husband. He thinks he's a dog!"

"I'm coming over right away," the doctor says.

When the doctor arrives, the woman opens the door, and her husband, on all four, starts wagging his bottom and licking the doctor's hand.

"Interesting", the doctor says, startled. "I'll examine him. Make him lie down on the sofa."

"Doctor", the woman says, "I can't! He's not allowed the sofa!"