Green’s Dictionary of Slang

(US campus) the library; as v., to attend the library; thus brary dog, someone who studies in the library.

1968		Current Sl. III:1 5: Brary, v. To go to the library.
1981		Eble Campus Sl. Fall 2: brary – library.
1996		Eble Sl. and Sociability 36: Slang words formed by clipping sounds from the beginning of the word are brary, from library. [...] 70: Dog is often the second member of a compound or phrase: brary dog ‘someone who studies in the library’.
2014		C. Eble (ed.) UNC-CH Campus Sl. Spring 2014.