Shake all ingredients with ice. Strain into chilled coupe. Garnish with fresh hot pepper slices.
The hot sauce (I used Inferno Farms Pineapple XXXpress) is a necessary finishing touch that only occurred to me after tasting the first iteration. Use something flavorful with a hint of sweetness, rather than just a Scoville bomb.
To get watermelon juice: For just one or two drinks, scoop or spoon out chunks of watermelon into a citrus press, such as a handheld lever type, and press firmly over your jigger or a glass. You should get about as much juice per squeeze as you would from half a lime. For a larger batch of juice, blend the watermelon, and strain through a fine sieve.
I pretty much just threw this together out of pure curiosity, and the desire to dig into the watermelon half sitting in my fridge. The flavors evoke memories of southern barbecues - smokey grills, juicy melon and a little kick of heat. Plastic red and white gingham draped picnic table optional.