Heat the olive oil in a large skillet. Add the onion and bell pepper, and saute until softened. Add in the ground beef, and cook until it is browned and cooked through. Drain any accumulated fat, if needed. Stir in the pizza sauce; heat and cook for about 10 more minutes.
Serve on hamburger buns with a good sprinkle of cheese. If you want it to get all melted, you can top the bottom bun and stick under the broiler for a few minutes. Also, you can toast the buns if you prefer. Eat!
Notes
You can easily stretch this to 5 Pizza Sloppy Joes!