Get your guests ready for the signature cocktail of Barbados.
Combine the first 3 ingredients in a big pitcher and stir until the sugar dissolves. Cover the pitcher and chill it in the fridge until it's ready to serve.
Divide the rum mixture among 4 ice-filled glasses. Stir 1 1/2 tablespoons of ginger ale into each serving. Garnish the glasses with fresh lime or pineapple slices, if you like.