In a large skillet, cook the bacon over medium heat for 5 minutes. Add the onion, celery, bell pepper and garlic and cook until the vegetables are softened, about 7 minutes.
Push the vegetables to the side of the skillet, then increase the heat to high. Add the ground beef and cook, stirring to break up any clumps, until cooked through, about 7 minutes. Stir in the ketchup and Worcestershire sauce and cook until thickened, about 5 minutes more. Season to taste with salt and pepper and serve on the toasted buns.