Censuring Stalin at a public meeting, Khrushchev was interrupted by a voice from the audience. “You were one of Stalin’s colleagues,” shouted the heckler. “Why didn’t you stop him?”

“Who said that?” roared Khrushchev. There was an agonizing silence in the room. Nobody dared to move a muscle. Then, in a quiet voice, Khrushchev said, “Now you know why.” (The Little, Brown Book of Anecdotes, ed. Clifton Fadiman)