Drinks on a bar.
What It Means To Request A Back Drink At The Bar
The word "back" is a surprisingly vital term in bartender lingo. A "back drink" is typically a non-alcoholic drink paired with stronger, higher-proof cocktails.
Your back drink can even be water, which pairs well with Manhattans and Old Fashioneds, letting these sometimes overbearing drinks shine without competing with their flavors.
"Beer backs" are also common for on-the-rocks spirits. If you order a Jack and Ginger short, you might also order a beer for sipping to help it go down a little easier.
Back drinks can be as small as a shot or come in a full pint glass. When ordering one, simply say something like "I'll take an Old Fashioned with a water back."