Eugene's easy crock pot beef barbecue is made with an inexpensive pot roast. The roast is cooked low and slow with some cola, ketchup, and onion soup mix. Only four ingredients make it a breeze to prepare, and the slow cooker makes it practically hands-free. Liquid smoke comes in a variety of flavors, including applewood, oak, and mesquite. For a smoky flavor, add a teaspoon or two of liquid smoke or season the beef with smoked barbecue seasoning.