Combine the whiskey, lemon juice, lime juice, and syrup. Fill a cocktail shaker halfway with ice and pour in the drink mix 2/3 full. Shake for 15 seconds and pour into glasses. Add a maraschino cherry and serve ice cold.
Note: To make the sugar syrup, bring 1 cup of water and 1 cup of sugar to a boil, and simmer until the sugar is completely dissolved. Chill before using.