This tart and refreshing cocktail is ideal for summertime entertaining. To make it, combine 2 ounces of Papagayo Anejo or Spiced Rum, depending on your preference, 1 ounce of juice squeezed from a fresh grapefruit, a squeeze of fresh lime, and two dashes orange bitters in a shaker with ice. Stir. Pour into a highball glass and top with soda. Garnish with a lime.