Coat a skillet with non-stick cooking spray; heat over medium high heat. Crumble in ground beef and cook for 8 mins. Stir in tomato sauce, ketchup, vinegar, Worcestershire sauce and sugar. Simmer on medium-low heat for 10 mins, stirring now and again. Serve over hamburger buns. For other variations: Italian : Add oregano, Italian seasoning, mozzarella, and use marinara sauce instead of ketchup. Serve over a pizza shell instead of a bun. Asian: Add 2 cloves of garlic, a half tsp. of ginger and substitute 2 tablespoons of light soy sauce for the Worcestershire sauce.