Sambuca is an evil evil aniseed liquer. I love it. Maybe it’s a hispanic thing? It’s pretty popular over here, it’s incredibly alcoholic.
We have a double shot called Sol Y Sombra (Sun And Shade). You basically put the Sambuca in first and then add some rum, the dark rum goes to the bottom and the Sambuca neatly rises to the top. A word of warning though, they are DEADLY.
Oh you can also do the trick of wetting your mouth with Sambuca and setting it alight but I wouldn’t recommend it kids.