The Sam Vimes
The Sam Vimes is a non-alcoholic cocktail first devised by his valet, batman, butler and gentleman's gentleman Willikins, a man who appreciates his master's needs.
The precise ingredients are unknown, but it is believed beetroot joice, cucumbers, and other useful kitchen staples and flavourings are combined together to create a palatable and agreeable beverage that acceptably mimics the effects of alcohol whilst containing none at all. After Sam Vimes is hailed King of the river for saving the boat the Wonderful Fanny and all on her in the face of the river Quire going into Old Treachery mode, copious quantities are made up and served during the celebratory party. Even Sam Vimes drinks several and feels drunk for the first time in years and has to be put to bed. It would appear this soft drink is going to rise in popularity and become fashionable. Sam would be well advised to copyright it.
After some investigation, the best available Roundworld version appears to be this, ginger and tabasco optional. The Nanny Ogg's Cookbook caveat applies, though, as it does to any recipe for food or beverages imported from the Disc. If it isn't watered down for our own safety, we may only, alas, approximate.