Riddle: A man was found dead in his office, with a gun in his hand. and there was a cassette on the desk. when the detective came and pressed the play button the cassette said: "I have nothing to live for, I should die". then there was a sound of a gunshot. how did the detective right away know that this was a murder and not a suicide?
Answer: Someone had to rewind the tape in the cassette so that when the detective played it; it had to be rewound.