It's also a layered cocktail / shot with coffee liquor (Kahlua is my fave), Irish cream (Baileys) and triple sec (orange liqueur like Grand Marnier or Cointreau).
I started off with a Lucky Charms shot which included OJ, Vodka, and Cointreau, and then moved on to a Shamrock - a-Rita made with Melon liqueur, and finally the Patties Crush, a gin - based drink you could get on the rocks or frozen.