On the way to my mother's house for Thanksgiving dinner, my wife was on her phone and noted that Old Navy was going to be open for Black Friday sales starting on Thursday at 3pm. Many people lament the fact that stores are open very early the day after Thanksgiving or, as it seems, even open on Thanksgiving day itself. The owners, managers, and employees of retail stores presumably would enjoy spending Thanksgiving with their families instead of preparing for Black Friday sales, yet almost every store announces that it will open very early on Friday morning for shoppers. How might game theory offer an explanation for this unexpected behavior?