In the bottom of a large pitcher, using a wooden spoon- crush the mint leaves, sugar and lime juice together. Stir in the rum and club soda.
Serve immediately in individual glasses over crushed ice.
Notes
If you're not in the mood to squeeze a zillion limes to create two cups, try using Nellie and Joe's Famous Key West Lime Juice, which is available in most major supermarkets. Or you can at least use part Nellie & Joe's and part freshly squeezed.