You know this story. Two prisoners in separate interrogation rooms. The first one to confess gets the lesser sentence. But if both stay quiet they both get off. Here is an Interactive Tutorial on "The Prisoner's Dilemma
Notes from the site:
"The Prisoner's Dilemma is a simple game in which there is a tension between individual interests and the common good. It has been studied in Economics, Philosophy and Machine Learning, and its lessons are potentially crucial for understanding human relations, evolution and morality."