Kevin Shay, in Reader's Digest
"Doc, you've got to help me!" came the frantic call to the psychiatrist. "They guy next door thinks he's in an opera. He sings day and night at the top of his lungs. It's driving me crazy!"
"Send him to me," said the shrink.
A week later, the caller phoned again, sounding much calmer, "Doctor, I don't know how you did it, but he's not singing anymore. Did you cure his delusion?"
"Not exactly," the psychiatrist replied. "I just gave him a much smaller part."