Now considered the national drink of Brazil, the Caipirinha was not always so respectable. In fact, the name comes from a somewhat derogatory word roughly equivalent to hillbilly. The cocktail's main ingredient, cachaça, is an aguardiente that, like rum, is made from sugarcane. But cachaça has a bite and flavor more characteristic of a rough-edged tequila than of its more refined cousin. In fact, bartenders who run out of cachaça have been known to substitute equal parts white rum and white tequila in its place. A Caipirinha is usually made by muddling pieces of lime with sugar; we chose, for simplicity's sake, to juice the limes instead. For a more authentic flavor, you can mash a piece of lime rind in the bottom of the glass before serving.