Pizza Hut, in my experience, hires Shift Managers both through their website and from their current employees, the latter of which was my experience. I worked as a driver from September through December. Even though this was my second job, I worked extremely hard, always stayed on task, and tried to lift everyone's spirits. Also, even though I did not approve of all of the decisions and behavior of one of our young shift managers, I stood up for him when he came under fire. Unbeknownst to me, this shift manager would be tapped to lead a new store in the area. After I heard him hint that he'd like me to be part of his time, I asked him officially for the job, and I received it, even though his boss was unsure of promoting me at first.
Keep in mind that this culture resembles high school in some ways. Stay classy and professional yourself, but also know that many people - even your bosses - may be a little immature. Have patience. This is your job, not your social network, and we're all a little imperfect and broken. So, give grace to those around you. It's a good idea in general, and (you never know!) it might even help you get a promotion.