Green’s Dictionary of Slang

bang and biff n.

syphilis.

1935		A.J. Pollock Und. Speaks 5/1: Bang and biff, sif., (syphilis).
1944		Maurer & Baker ‘“Aus.” Rhyming Argot’ in AS XIX:3.
1960		J. Franklyn Dict. of Rhy. Sl.
1978		Maledicta II:1+2 (Summer/Winter) 118: He [...] also lists: [...] Bang & Biff Syph[ilis].