Take one quarter of a very nice ripe lime. Squeeze it into your favorite glass.
Add about that much Blackstrap Curazon Navy Rum. If you haven't had this rum, find some and make yourself happy. It's not too pricey and has the most interesting flavor.
Add a spoonful of sugar. Stir, stir, stir.
Add enough icy cold seltzer to get to about halfway up the glass.
Fill the rest of the glass with ice cubes.
Repeat as necessary or until mr. delagar makes you stop.