Sambuca

Sambuca, also spelt "Sambucca", is an anise-flavored liqueur. It is usually a clear liquid. This is often referred to as "white sambuca" in order to differentiate it from derivative spirits that are deep blue in colour (known as "black sambuca").

Sometimes drunk as the flaming sambuca as follows: the shot of Sambuca is taken into the mouth, ideally without spilling over lips, chin, chest, hair etc. An assistant sets it on fire, typically with a lighter. The alcohol is allowed to burn off for a while, then then mouth is closed to quench the flame and it's swallowed.

see also the Wikipedia Cocktail Guide