He thinks he's a refrigerator
A woman goes to a psychiatrist and says, "Doctor, you've got to do something about my husband. He thinks he's a refrigerator!"
"I wouldn't worry too much about it," the doctor replies. "Lots of people have harmless delusions. It will pass."
"But you don't understand," the woman insists.
"He sleeps with his mouth open, and the little light keeps me awake."