Dirty Girl Scouts are my favorite shot at the bar; it tastes like those Girl Scout mint cookies. Admittedly I'm a little fuzzy on the recipe, but I've been told this is how it goes:
Equal parts each of Vodka, Kahlua, Bailey's Irish Cream and a "half part" Creme de Menthe (use green to give it that "girl scout uniform" color).
I prefer this in a shot size. (I don't know if it's ever made larger?)