cag, v. — Green’s Dictionary of Slang

cag v.

also keg

[dial.]

1. to irritate, to annoy.

1801		in Southey Letters 1 (1856) 149: Pray do not cag Horne Took [sic] for the sake of the debates [EDD].
1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict.

2. mid-19C to abtain from alcohol.

1855

Bombay Gaz. 3 Aug. 4/2: Many of them had adopted a disgraceful custom, well known in some regiments by the slangnlame of cagging [...] ‘Cag’ we believe to imply [...] an abstinence for a limited and fixed period, from the use of ardent spirits.

In derivatives

cagged (adj.) (also kegged)

irritated, angry.

1811		Lex. Balatronicum n.p.: Cag. To be cagged. To be sulky or out of humour.
1821–6		‘Bill Truck’ Man o’ War’s Man (1843) 247: Oho! – kegg’d – kegg’d already [...] I’d no idea I’d strike fire out of the old flint so smartly.
1830		W.T. Moncrieff Heart of London II i: I declare he’s not like the same man. [...] cagged about my putting the rogues in spirits.