Lightly moisten the mint sprig and sprinkle with sugar. Set aside.
Fill a Collins glass with ice. Pour in orange juice, lime juice, lemon juice, and pineapple juice. Stir until the glass is frosted. Add light rum and Jamaican rum; stir until combined. Top with triple sec and grenadine. Garnish with slices of orange, lemon, pineapple, maraschino cherry, and the sugar-dipped spring of mint. Serve with a straw.