For the most part, kids that age not only don't think about consequences, but they enjoy being controversial because it gets them attention/admiration from friends. They hang in packs, and have a herd mentality. They are half-baked at best and likely thought that a theme involving cool hats and big 'old-fashioned' dresses and a confederate flag and guns would make hem "rebels" and give them instant cred among their peers at school. You know, the important stuff at that age.