1 cup sugar
1 cup water
3 1/2 cups seeded, cubed watermelon
3/4 cup tequila
1/2 cup fresh lime juice
Bring sugar and water to a boil in a medium saucepan, stirring until sugar dissolves; boil 1 minute. Remove from heat; cool.
Process watermelon in a blender until smooth. Combine all ingredients, and shake well.