Preheat oven to 350°F (175°C).
In a skillet over medium heat, cook ground beef and onion until the beef is browned and onion is soft. Drain excess grease.
In a large bowl, combine cooked beef mixture with ketchup, BBQ sauce, mustard, and brown sugar. Stir until well combined.
Add all three types of beans and stir to combine.
Pour mixture into a 9x13 baking dish. Top evenly with crumbled bacon.
Bake uncovered for 1 hour, until bubbly and slightly caramelized on top.
Serve warm and enjoy!