I think it's a thing for people who drink scotch or whiskey. They'll add a single drop of water to "open it up" (whatever the heck that means). But not ice cubes, because that dilutes it. If they *must* cool it down, they use "whiskey rocks" which are little granite spheres you can chill in your freezer, and impart cold without dilution.
Me, I drink chocolate cream rum over ice cubes, because 14% alcohol is way too strong for me! And I could probably only drink whiskey as one drop of whiskey in a glass of water! Lol.