Fill a Collins glass or a Moscow Mule mug with ice. Squeeze lime juice into the glass and drop in the spent shell.
Then, pour in the rum and top with ginger beer. Stir gently. Garnish with another lime slice, if desired.
Notes
Use a zero-proof rum instead of dark rum to make this recipe non-alcoholic.Impress your guests by "floating" the rum on your drink like a storm cloud. Do this by pouring the liquor slowly over the back of a bar spoon and serving the drink (stir before sipping!)