Combine sugar and water in a small saucepan; cook over medium heat, stirring constantly, until sugar dissolves and mixture comes to a boil. Boil 5 minutes without stirring. Cool. Stir in lime juice.
Combine sugar mixture with fruit punch and rum. Serve over crushed ice.
*In testing, we used 1/2 cup Myers'sRum and 1/2 cup Mount Gay Extra Old Barbad