Do Halloween right...Spooky and simple, this is a classic margarita recipe made with 1800 silver tequila, fresh lime juice, Cointreau, and some tweaks to get the color just right. Also- I did not end up with purple teeth after drinking...in case you were worried. I also love the way the sugar rim looks like crushed amethyst. Fun drink!Look for black or dark purple decorating sugar, if you can't find it, add sugar to a baggie and squish it around with food coloring to achieve the color you…