Remember the Telephone Game?
You can read all about it here, but the gist is the first person is whispered a message. That person then whispers the same message (to the best of their recollection) to another person. The process continues until the last person receives the message. At that point, the last person announces the message for all to hear. The fun part of this game is to hear how much the story changes as the message is passed from person to person.