Mix ketchup, beer, Worcestershire sauce, and bay leaves together in a slow cooker (such as Crock-Pot(R)) set over High. Form ground beef into meatballs. Heat a skillet over medium-high heat and cook meatballs, turning as needed, until browned, about 7 minutes. Place meatballs in the slow cooker. Cook on High until sauce is thick, about 5 hours. Remove bay leaves before serving.