Green’s Dictionary of Slang

(US) a bank roll.

1915		T.A. Dorgan in Zwilling TAD Lex. (1993) 19: Ain’t cha — take the rubber off the old b.r. and buy?
1940		D. Maurer Big Con 159: He has official custody of the ‘B.R.’ or ‘boodle’.
1949		Monteleone Criminal Sl. (rev. edn).
1969		‘Iceberg Slim’ Pimp 109: I got enough ‘B.R.’ to raise you fast.
1979		‘Iceberg Slim’ Airtight Willie and Me 10: At least until I got [...] B.R. (flash cash) and threads to dazzle.