Ye Gods and little fishies.
Two ounces of white rum
One teaspoon powdered sugar
Four to eight mint leaves
Dump your mint leaves and sugar in the bottom of your glass. Mash the leaves and stir them into the sugar pretty well (called 'muddling').
Fill the glass with crushed ice, add your rum and squeeze that lime mercilessly over the rum. Drop the battered remains of the lime into the glass.
Top with club soda, stir, add a sprig of mint for sophistication.
Voila! The Mojito. Enjoy under air conditioning.