Another Thanksgiving, another Black Friday: This once-a-year retailing event is now as common as turkey and pumpkin pie during this holiday weekend, with many retailers trying to get a head-start by opening on Thanksgiving Day. It also brings out the worst in American civilization, with news of violence at shops now a yearly occurrence in some locales. So, before you rush out to try to score a deal on some no-name Blu-ray player, ask yourself, is it really worth it? Here are some images from Black Friday past of things spiraling out of control – some gruesome enough to make you want to stay home and spend time with the family. You know, that thing you used to do?