Margarita Man® Watermelon mix concentrate. All the juicy fun without the seeds. Our Watermelon concentrate is now made with all-natural flavoring. One half-gallon of concentrate produces 3.5 gallons of frozen Watermelon slushies and yields 56 drinks (8 ounces each) with alcohol mixed in, or 48 non-alcoholic slushies. Check out our Watermelon Mixing Guide for more info.