(Noun): an empty water bottle filled with vodka, stored in a purse for easy access while occupying restaurants, bars, clubs, airplanes, golf courses, etc. Often times the vodka is of the flavored variety; or Belvedere.
Similar to the ones Ke$ha sings about in her songs, only it's vodka rather than whiskey.
(Verb): the act of getting drunkles in public places despite being a broke law student.
Law Student #1: I really want to get drunk on Park Ave tonight, but all the good drinks are like $20.
Law Student #2: Have no fear, purse vodka is here!