Green’s Dictionary of Slang

to hit; thus slosher n.; thus slosh the burick/slosh the old gooseberry v., to hit one’s wife.

1870		Graphic 26 March in R.T. Hopkins Life and Death at the Old Bailey (1935) 95: Another slang verb, ‘sloush,’ puzzled the court [...] The policeman rushed forward, and one of the thieves cried, ‘Sloush him!’ The meaning was at once exemplified.
1882		‘Blooming Aesthetic’ in Rag 30 Sept. n.p.: A slosher-of-pals, / A spooning-with-gals, / An ought-to-be-blowed young man.
1892		Kipling ‘Fuzzy-Wuzzy’ in Barrack-Room Ballads (1893) 151: We sloshed you with Martinis, an’ it wasn’t ’ardly fair.
1905		Sporting Times 15 Apr. 2/3: They’ve got old Daddy Mills inside for sloshin’ one o’ the King’s physicians.
a.1909		press cutting in J. Ware Passing Eng. of the Victorian Era 129/2: Put on a fiddle-face and jaw to him about his future, and it’s most likely he and his mates will slosh your mug for you and sneak your yack. [Ibid.] 226/2: Slosh the burick (Common London Life). Beating the wife. [...] Slosh the old gooseberry (Low. London). Beat the wife.
1912		Sat. Referee (Sydney) 12 Oct. 4/6: The fact of having beaten an opponent can be described as having [...] ‘sloshed him,’ ‘smashed him,’ ‘gravelled him,’ ‘laid him out’ [etc] .
1919		Wodehouse Damsel in Distress (1961) 58: Slugged a slop. Most dramatic thing. Sloshed him in the midriff. Absolutely.
1929		(con. 1916) F. Manning Her Privates We (1986) 152: ‘Take that you fuckin’ bastard!’ says Madeley, an’ sloshes ’im one in the clock.
1934		Wodehouse Right Ho, Jeeves 126: Let us now suppose that you sloshed that tiger cub.
1934		Derby Dly Teleg. 11 Dec. 1/3: Masncini’s Alleged Advice on ‘Sloshing’ Women [...] Why knock women about with your hands. You only hurt yourself. Hit them with a hammer and slosh her out.
1941		G. Kersh They Die with Their Boots Clean 124: If you could [...] slosh ’im when ’e’s too blind to see you.
1959		I. & P. Opie Lore and Lang. of Schoolchildren (1977) 128: Charlie Chaplin meek and mild / Took a sausage off a child, / When the child began to cry / Charlie sloshed him in the eye.
1962		F. Norman Guntz 91: The next thing I knew one of them had sloshed Moe.
1979		(con. 1930s) J. Wolveridge He Don’t Know ‘A’ from a Bull’s Foot 8: If he had said ‘Piss off’ she would have sloshed him with a saucepan.