As legend has it (or Wikipedia, which is basically legend), Reggie Cunningham coined the term pickleback at Bushwick Country Club in Brooklyn in 2006.

Such a weird but simple idea, the type which you swear maybe you tried once or twice long before 2006 but were too drunk to really recall. But you probably didn’t: Rob Magill, co-owner of Whiskey Town and its family of bars in New York, also believes that “the latest craze of pickle juice that inspired everything from cheap shots to high-end cocktails” goes back to Cunningham, so let’s just settle it and say Cunningham is the genius that came up with the idea.
The pickleback is simple: a shot of whiskey followed by a shot of pickle brine, that’s it. And in just ten years it has become a familiar pairing with bartenders around the world. But as they’re finding out, pickle brine can be used for more than just shots, and maybe should become a permanent part of your bar. We asked Magill and Filip Keuppens of the Pickle Juice Company about how to integrate the ingredient into more than just shots — though those aren’t so bad on their own.