As I was entering drinking age (OK, maybe I wasn't quite 21, but Staten Island was only 18 anyway) growing up in central New Jersey, a common, maybe most common, way to order a drink was "whiskey, beer back" or "scotch, water back." The "beer back" was much more prevalent than all others combined. More particular drinkers might ask for a "VO, beer back" or when I wanted to show my chops, "Beefeater, beer back."
The "beer back" was always a small, 7 oz. glass of draft beer, whatever was on tap.
As far as I can tell this must have been a regional procedure, as all other places would have that ordered as two separate drinks.
Anybody familiar with this terminology or anyplace the still practices it?