Green’s Dictionary of Slang

1. (also brush about) to have sexual intercourse.

c.1785		‘Connelly’s Ale’ in A. Carpenter Verse in Eng. in 18C Ireland (1998) 387: Brush her up tight, I’ll be bound she won’t fail.
1793		Bacchanalian Mag. 9: I often repeat these sweet visits to Kate / [...] / [W]e’ll brush it about, / At morn, noon and night, ’till the brush is worn out.

2. (US black, also brush up) to defeat, to overcome; to beat up.

[1826		‘Nocturnal Sports’ in Universal Songster II 180/1: Ri tum ti tum tum / With a game fistic brushing].
1939		Pittsburgh Courier (PA) 16 Sept. 11/1: Bailey [...] brushed up his honey a little too often .
[1940		M. Marples Public School Slang 15: Few slang expressions are used of birching as distinct from caning (seecake), but the following may be noted: brush].
1941		Pittsburgh Courier (PA) 22 Feb. 7/1: Sally Gooding, whose ole man brushed her up lightly , leaving her right optic a bit on the dark side.
1944		in ‘The Jiver’s Bible’ in D. Burley Orig. Hbk of Harlem Jive.
1960, 1975		Wentworth & Flexner DAS.

3. (N.Z. prison) to stab.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 31/2: brush v. to stab someone.