Cut the watermelon flesh into chunks and, working in batches, puree in a blender unti liquified. Strain through a fine sieve to remove the pulp; you should have about 4 cups of juice.

Combine the watermelon juice and the lemonade in a 2 quart pitcher

To make individual cocktails, fill a shaker with ice. Add 1 cup of the watermelon-lemonade micture and 2 ounces of alcohol. Shake vigorously. Strain into a tall glass filled with ice or chilled martini glass