Trim off the excess fat from the venison. In a large bowl mix the beer, garlic, salt, pepper, onions and bay leaves; add venison. (Marinade should cover meat) Marinate in the refrigerator for 12 - 24 hours, turning occasionally. Remove the venison and onions from marinade and place into a crock pot. Pour 1 cup of barbecue sauce over the top. Cover and cook on low for 10 - 12 hours. Serve with the remaining Barbecue Sauce. Serves 6.