The Anonymous Threat

"Uh Oh!" said an ardent young man reading a letter.

His friend, standing near him, said, "Bad news?"

"Disturbing news, anyway," said the young man. "It's from someone who says if I don't stay away from his wife, he'll kill me."

"In that case, if I were you, I would stay away from his wife."

"Gladly, but who? The letter is anonymous."