Green’s Dictionary of Slang

1. fake Latin.

1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1824		Dublin Eve. Mail 27 Dec. 3/3: A little bog Latin, commonly called Priest’s Latin.
1830		Dublin Morn. Register 5 Aug. 2/4: So much for the English of this adept in bog Latin [...] This the ‘bookful blockhead’ takes to be right reasoning [etc.].
1832		Satirist (London) 27 May 171/2: The Tipperary Correspondent of Morning Herald calls the Tithe Question the irrito maula malorum. Sir Claudius calls this Bog Latin, and declares he cannot understand it.
1840		Eve. Chron. 25 Sept. 3/6: A speech of Mr O’Connell [...] makes the learned gentleman discourse bog Latin at a fine rate.
1858		Kilkenny Jrnl 17 Apr. 2/3: When he thinks fit to introduce a priest he is represented as a man delighting in whiskey punch and comic songs [...] interlarded with bog Latin.
1862		Tralee Chron. 7 Jan. n.p.: It seems but the other day that we were finally rid of John Doe and Richard Roe [...] and of John A’ Noakes and John A’ Styles in chancery proceedings; when indictments wee drawn in bog Latin and declarations in bastard Norman French.
1866		Montana Post (Virginia City, MT) 2 June 2/2: The writer [...] closes [...] with what hje intends as humorous: ‘Hick jacket Virginia.’ Bog Latin, we presume.
1875		Pacific Commercial Advertiser (Honolulu, HI) 24 Apr. 4/3: There are gushing visiting cards [...] some with bog Latin mottoes.
1887		Grantham Jrnl 5 Mar. 8/4: I wonder if he picked up that bit of ‘bog Latin’ whilst on board ship.
1892		Inianapolis Jrnl (IN) 21 Feb. 13/1: He even attempted a serio-Latin comic pun [...] a witticism wholly lost upon the commissioners, who didn’t even have knowledge of bog Latin.
1895		Truth (Sydney) 17 Feb. 1/8: Medieval monks and friars limited their learning to chanting bog Latin and indicting treatises on [...] excorcism .
1904		Chanute Times (KS) 16 Sept. 2/6: Darcy was a bit of a bog Latin scholar.
1914		Eve. World (NY) 23 Jan. 16/7: The way they sounded when announced was like bog-Latin to me.
1922		Joyce Ulysses 382: He was a lefthanded descendant of the famous champion bull of the Romans, Bos Bovum, which is good bog Latin for boss of the show.
1994		V.B. Evans House in the Faythe 122: We were convinced for years that my father could speak German and a smattering of what he called bog-Latin.

2. tinkers’ Gaelic.

1958		(con. 1940s) B. Behan Borstal Boy 311: Giving out of you in bog Latin about the Bible.
1979		J. Morrow Confessions of Proinsias O’Toole 74: Fuck you an’ yer bog Latin, Francie Fallis, you stinkin’ bastard!
2000		N. Griffiths Grits 318: She only ever uses the Bog latin now when she’s talkin to erself or er dead husbands.