Desmond Young, a 50-year-veteran bartender at Jamaica's Strawberry Hill resort, uses two kinds of rum in his signature drink -- a dark variety and a potent white rum that, at 126 proof, adds a real kick to this cocktail.
Combine sugar and water in a small saucepan. Boil for 5 minutes. Let cool.
Combine lime juice, both rums, bitters, ice, and 1/4 cooled sugar syrup in a large cocktail shaker. Shake well to combine. Pour into a glass. Garnish with swizzle stick.