Green’s Dictionary of Slang

a boon companion; thus jolly-doggy-ness; also attrib.

1708		Humours of a Coffee-House 2 Jan. 84: Honest Jack, thou’rt a Jolly Dog yet, I see.
1788		J. O’Keeffe Prisoner at Large 28: Here’s two bottles for the jolly dog.
1799		‘Poll of Wapping Stairs’ in C.L. Fraser Chap Book (1920) Sept. 15: Her father he’s a jolly dog / Poll keeps him spruce and brews his grog.
1809		Morn. Post 4 Dec. 3/3: he entered the office with the manners [...] of what is generally termed a jolly dog, or knowing one, and by some he would have been called a rolling kiddy.
1812		‘Hector Bull-us’ Diverting Hist. of John Bull and Brother Jonathan 55: These jolly dogs thought it would be a good joke to quiz John a little.
1821		Egan Life in London (1869) 43: May jolly dogs point to me under the table. / And say, with a sigh, ‘That’s Tom Sheridan’s dad’.
1827		Australian (Sydney) 14 Feb. 4/3: We have lately been regaled with a numerous importation of care-killing jolly dogs of government civilians.
1836		Australian (Sydney) 8 Nov. 4/1: We’ve lark’d, got gay, my faithful chum, / With song and grog, / And box’d each Charley, knave and bum, / My jolly dog.
1838		‘Uncle Sam’s Peculiarities’ in Bentley’s Misc. IV 297: Living that sort of life which, in England, is called that of a jolly dog.
1840		‘Ben Backstay the Boatswain’ in Lover’s Harmony No. 18 141: Our captain, who was a jolly dog, / One day he gave to every man a double share of grog.
1861		T. Hughes Tom Brown at Oxford (1880) 59: Some runaway apprentice, I take it, but a jolly dog.
1877		J. Greenwood Dick Temple I 4: An indescribable, free-and-easy, jolly-doggy-ness of demeanour.
1879		‘’Arry in Parry’ in Punch 15 Nov. 217/1: The French don’t seem up to perdoocing us cards of the jolly-dog stamp.
1880		E.J. Milliken ‘Cad’s Calendar’ in Punch Almanack n.p.: Rare old time for regular jolly dogs.
1880		Bulletin (Sydney) 10 Apr. 3/3: If we wore our Sunday togs, / We shouldn’t be such jolly dogs.
1907		Times Dispatch (Rirckmond, VA) 30 June 35/3: But what cared they, the Jolly Dogs. / They thought they were quite knowing.