Triple Sec is an orange flavoured liqueur used cocktails like the Cosmopolitan, Margaritas and Long Island Ice tea and many other delicious cocktails. Meaning, "triple distilled," triple sec is made from the dried peels of bitter and sweet oranges. Triple sec can be served neat, on the rocks or as mixer for a variety of cocktails. If you are to buy just one liqueur, you might want it to be triple sec as it's extremely useful in the bar.