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1.
The volume of alcohol which can be consumed within one hour.

Similar to "light year", vodka hour is not a description of a temporal unit, instead it refers to the universal constant of the volume of vodka consumable within a full hour.
Guy 1: "Dude, we've drank a lot of Red Bull, how much vodka will it take to even it out?" Guy2: "A quarter of a vodka hour I reckon"
by vodka drinker March 03, 2011