A pickleback is a type of shot wherein a shot of liquor is chased by a shot of pickle brine; the term "pickleback" may also refer only to the shot of pickle brine itself. Alternatively, the shot can be chased by a bite of a pickle (generally, a whole dill pickle). The pickle brine works to neutralize both the taste of the liquor and the burn of the alcohol.[1]
British visitors returning to the United Kingdom from New York City introduced the recipe to bars in both London (as early as 2011),[2] and Devon. In 2012, UK bartender Byron Knight created a bottled pickleback using his own homegrown dill pickles and a flavour profile of ginger, mustard seeds, dill, garlic and dark sugar.[3]
The drink has also spread to Canada,[4] Shanghai,[5] Belfast and New Zealand.[6]
https://archive.nytimes.com/tmagazine.blogs.nytimes.com/2010/03/16/case-study-got-your-pickleback/