Watermelon Rum Cooler

"This easy to make slush is perfect for enjoying when entertaining, while summer grilling, at barbecues or just enjoying at home in hot weather. It's also perfect for game day entertaining or tailgating. Using watermelon. limes, 7UP and ice, use your blender to mix up this superb slush. Add your favorite rum for a delicious adult cocktail, or leave the rum out for a delicious drink that all ages can enjoy. It's a hit either way! "