Much of the art of rhetoric revolves around building a connection between different people—and, at the same time, excluding certain groups of people. As every third grader knows, one of the strongest ways to make a group of friends is to exclude other students. By laughing at the excluded people, a group reminds itself of its common cultural bond, whatever that bond might consist of. And this concept has much more sinister applications as well, of course, resulting in racism, prejudice, and violence.