Green’s Dictionary of Slang

(US campus) a bloody Mary, a drink of which the chief constituents are vodka and tomato juice.

1982		G.V. Higgins Patriot Game (1985) 27: We will sit down and have a bloody and then a piece of fish or something.
1985		E. Leonard Glitz 174: You want another Bloody?
2011		Chicago Trib. 18 Aug. 6/1: It would be enough to sip this bloody ($6-$8) without the beer.