Proof is a measure of the alcohol content of a beverage. In the U.S., policymakers define proof as twice the percentage of alcohol by volume (ABV). For example, a drink with 40% ABV is 80 proof.
It's a freezing winter night in early February, but inside a chic restaurant perched atop a tower in Manhattan's labyrinthian Financial District, Jim Gaffigan is regaling a crowd of liquor journalists ...