Green’s Dictionary of Slang

1. (also cag magg, kag-mag) refuse, rubbish, odds and ends; usu. of food scraps; thus cagmag (and) snivellers, an unappetising dish of second-rate, even rotten meat and fried onions (which stereotypically make one snivel in their raw state).

[1786		Grose Classical Dict. of the Vulgar Tongue ms additions n.p.: Cagg Maggs. Old Lincolnshire Geese, which having been plucked ten or twelve years, are sent up to London to feast the Cockneys].
1811		Lex. Balatronicum n.p.: Cag Magg. Bits and scraps of provisions. Bad meat.
[1824		Pierce Egan’s Life in London 26 Sept. 5/3: This new aspirant after milling honours is dry and sinewy as a cag-magg].
1825		Sydney Gaz. 3 mar. 3/4: I must endeavour to dispose of my cag-mag in some other market.
1829		Vidocq Memoirs (trans. W. McGinn) III 54: Snakes [...] do you want; cag-mag and snivellers (stinking meat and onions) would be as good.
1834		‘A Grand Turn-Up’ in Randy Songster in Spedding & Watt (eds) I 188: There vos Sam Fluefaker, the chummy, Salk Cagmag, the cat’s-meat gal, Bob the dustman, Ned Stirbaout, the nightman.
1835		G. Kent Modern Flash Dict. 8: Cagmag – stinking, or bad meat.
1841		‘Put Up Your Muck!’ in Gentleman Steeple-Chaser 27: Put up my muck – I’d have you know / I never do for cagmag go.
1850		N.Y. Herald 17 Feb. 2/4: CAUTION TO BUYERS – THE RIGHTS OF BUYERS. [how to shop for provisions] [...] the provision trade is engrossed by poor Germans, who have not the delicate taste of the Anglo-Saxons, and keep and buy in mere cag-mag.
1858		E. London Obs. 7 Aug. 2/2: We should expect the contracting burtchers to [...] buy their worst meat [...] and supply ‘cag-mag’ to the troops at a high profit.
1865		H. Kingsley Hillyars and Burtons (1870) 86: Jints, you understand [...] none of your kag-mag and skewer bits.
1866		Sportsman 1 Sept. 2/1: Notes on News [...] [A]ny meat [...] however diseased, will do for the London poor, who at present high prices are almost forced to buy ‘cagmag’.
1870		Hotten Sl. Dict.
1873		Sth Aus. Register (Adelaide) 20 Sept. 4/6: The penny dinner movement under which Australian meat mader its debut in London could not compete with ‘cagmag’.
1888		S.O. Addy Sheffield Gloss. 122: Keg-meg, poor meat, offal, worthless scraps of meat.
1895		Crowe Aus. Sl. Dict. 14: Cagmag’s Snivellers, stinking meat and onions.
1899		‘Pot’ & ‘Swears’ Scarlet City 132: Anthony [...] finally decided upon a menu which he described as ‘prime cag-mag’.
1908		Sun. Times (Perth) 26 July. 6s/1: The greedy gang of Boodle Bugs who control the State’s supplies of cagmag .
1912		Sun. Times (Perth) 25 Aug. 8s/6: Neath the old red, blue and white / Bull the cagmag loudly scorns, / While contentedly we bite / Ancient hoofs and crumpled horns.
1921		West. Argus (WA) 24 May 7s/2: High quality tells all the time: / Mere cheapness is merely a waste of good cash / On ‘cagmag’ which cannot endure.
1924		G.H. Lawson Dict. of Aus. Words and Terms 🌐 CAGMAG – Scraps of food.
1928		Sun. Times (Perth) 10 June 6s/4: The man who sold the sulphur dioxide, plus water, stale bread and cagmag was only fined £7.
1935		A.J. Pollock Und. Speaks 17/2: Cag-mag, scrap food of very poor quality (prison).
1953		J. Franklyn Cockney 182: Waiting in the meat queue for a ‘bit o’ cagmag’.
1956		Argus (Melbourne) 30 July 5/8: ‘What,’ asks Mr Arch E Cooper [...] is cag-mag?’ [...] It means a tough old goose or some form of inferior meat.

2. gossip, tittle-tattle; thus cag-mag man, a gossip.

1878		Edinburgh Eve. News 22 Nov. 4/3: The hardest job he had had [...] was to sit there month after month and listen to the ‘cag-mag’ of the members.
1902		Bulletin (Sydney) 6 Sept. 15/2: His friends always understood that he had political longings. A dull speaker of the kind of cag-mag that passes for oratory at A.N.A. meetings; otherwise, a decent fellow.
1906		Sun. Times (Perth) 11 Feb. 1/1: The condemner of cagmag is exposed equally to stoush of the wrath of wirepullers.
1915		Sun. Times (Perth) 12 Dec. 7s/2: Magisterial cagmag. ‘Whole walking...’.
1923		J. Manchon Le Slang.
1936		Sun. Times (Perth) 21 June 1/6: They say that the cag-mag man unfeelingly blew the gaff.