If you live in southern California, or know someone who does, then you're probably familiar with In N Out Burger. And if you're really in the know, then you know all about In N Out's "secret" menu that isn't all that secret, since the company has it posted on their website. Protein burgers, grilled cheese, and "animal-style."
However, the real secret menu behind fast food joints will never make it to the customers, because they are creations that the cooks make for themselves after hours. We're not even talking about In N Out here. McDonald's employees, as posted on an employee blog, make their own "McBruschetta" using ingredients that are normally reserved for your Big Mac, et al - buns, tomatoes, sliced onions. They even do things like use pancake batter to make funnel cakes in the French fry fryer.
If you ever wondered why it smelled like a bakeshop when you were ordering Pizza! Pizza!, it might have been the cookie dough that Little Caesar was baking in the pizza oven.
If I were locked in a McDonald's kitchen at midnight, I wonder what kind of "creations" I could come up with.