Cut the pink flesh from a watermelon, mash well, strain out the seeds and pulp. You'll want about a quart of juice. Juice 4-6 limes, add to watermelon liquid along with about 1/4 cup of sugar. (More or less; adjust to taste.) Combine with ice and as much vodka as you desire. Shake well(I shake fifty-five times). Strain into martini glasses, garnish with a thin wedge of watermelon. For an even zippier beverage, use pepper vodka. Zow!