Peel 2 of the limes.
Thinly slice the 2 limes. If your limes have seeds, remove them.
Slice remaining lime.
Place 2 peeled limes in shaker.
Add sugar to shaker.
Add mint leaves to shaker.
Add rum to shaker.
Shake - for about a minute, to dissolve the sugar.
Pour into glass.
Add remaining lime to glass. Save one lime slice for garnish.
Add additional ice to top off the glass.
Add lime as garnish. Enjoy!