This Gin Rickey cocktail is often claimed to have been the favorite drink of Fitzgerald (The Great Gatsby author), and is one of only two cocktails to be mentioned by name in the book.
1 1/2 oz gin
juice of 1/2 limes
1 lime wedge
Pour juice of lime and gin into a highball glass over ice cubes. Fill with carbonated water and stir. Add the wedge of lime and serve.