German for "winglet", or little wing; actually spelled Flügerl, but you're not supposed to put special characters into node names, are you. In certain regions of Austria, you can order a Fluegerl in a bar and will be served a long drink composed of Red Bull (an Austrian energy drink) and red vodka. In other regions it is called, umh... Red Bull with red vodka (please /msg me if you know some other names for it).
As Red Bull contains caffeine and taurin, it says "do not mix with alcohol" on its cans and bottles. Because of that, people of course like to mix it with alcohol very much; it feels like eating a forbidden fruit. But AFAIK it isn't really dangerous when not consumed excessively.
Tastes damn good, by the way.