The MacAbre
The finest - and most expensive - whisky available in Ankh-Morpork. Bottled by Jimkin Bearhugger's Whiskey Distillery, even a sniff of it is like Hogswatch. Sir Samuel Vimes once had to empty an entire bottle onto his carpet to foil an elaborate set-up. This, even more than the attempted entrapment, was enough to make him determined to catch the perpetrators.
Look here for the Unseen University bledlow of almost the same name.
Annotation
The prefix "Mac-" is attached to some of the finest Scotch single malt whiskies available. Examples include Macallan and MacPhail; some use the definite article (e.g. "The MacAllan"). Although there are far more decent whiskeys prefixed with Glen- or La-, Mac is authentically whiskyish, being definitively Scottish. The added twist (whisky with a twist? Behave!) is that the word Macabre means "Suggesting the horror of death and decay; gruesome".