Well this is pretty fascinating:
Years ago, before this type of activity was frowned upon, scientists sent 2 groups of 11 and 12 year-old boys to live in separate sections of an Eastern Oklahoma camp. The boys didn’t know about each other at first, and they quickly developed independent social hierarchies and social codes. One group named themselves the Rattlers. The other group didn’t pick a name until after the groups discovered each other. They chose the Eagles, an animal that eats snakes. The scientists ratcheted up the competition between the two groups, eventually losing control of the experiment as the boys were executing violent raids on each others’ camps. The scientists finally separated the camps before someone got killed, but not before documenting some interesting concepts of how groups form social norms and how they react to others they perceive as different.