For pickle lovers.
Before we start, a sidebar: The one time I tried taking a pickleback outside 1604, the enthused bartender tried to sell us on McCormick's vodka. No, sir. We passed on that offer.
While the history of the pickleback is a bit murky, The New York Times' Tom Cecchini credited its creation to Williamsburg, Brooklyn in 2010, and NYC bartender and consultant Jason Littrell (and SA Cocktail Conference staple) called the two-fer shot a "the pisky whickle."
Regardless of its origins, the pickleback combines whiskey (usually a sweet Jameson), and pickle brine. The tart pickle juice helps lessen the kick of the whiskey and alcohol, so try these at the beginning of the night to really get things going.