Green’s Dictionary of Slang

1. a general intensifier, extremely, very, exceedingly; esp. in dirty big, dirty great.

1781		‘Dick the Dustman’ in Bullfinch 7: And so d’ye see men bustle, / To see who’s dirty first, / And one another hustle, / And all to raise the dust.
1841		W.J. Neale Paul Periwinkle 39: Tut, man, don’t be so dirty particular.
1855		N.Y. Tribune 22 Oct. 6/1: It was a dirty big rat, bigger nor the cat herself.
1871		Bolivar Bull. (TN) 15 Apr. 1/3: The Slang of Our Day [...] They tell you ‘that game is quite played, say, walk, you dirty big loafer.’ Or ‘a head on you’ is sure to be made.
1881		Memphis Dly Appeal (TN) 17 May 1/6: Hubby, put on a clean shirt, you Dirty big villain.
1898		Anaconda Standard (MT) 2 Aug. 9/4: The dirty big brute.
1902		Broad Ax (Salt Lake City, UT) 16 Aug. 1/3: Murrays and Carey’s dirty big toes.
1914		Eve. Teleg. (Dundee) 2 Mar. 1/3: He is a downright liar and a dirty big —.
1920		J. Galsworthy Foundations 83: ‘’E wants to syve ’is dirty great ’ouse.’ ‘Damned if I do!’.
1933		M. Marshall Tramp-Royal on the Toby 107: I [...] spent a most horrible night trying to sleep in an old abandoned shack that was hotching with dirty big rats.
1941		G. Kersh They Die with Their Boots Clean 54: Just because you’re in the Army you think you can take all kinds of dirty rotten liberties.
1943		Baker Popular Dict. Aus. Sl. (2nd edn) 26: Dirty big, used adjectively as an equivalent of ‘bloody’.
1954		(con. 1940s) E. Lambert Veterans 203: Looks like a dirty big boil.
1958		F. Norman Bang To Rights 36: He lets out this dirty great scream.
1959		A. Zugsmith Beat Generation 30: She had a dirty rotten thing happen to her.
1963		(con. 1944) L. Glassop Rats in New Guinea 32: He comes out with some bloody beauts [i.e. lies] don’t he? You haven’t changed a bit, you dirty big bull artist.
1966		P. Willmott Adolescent Boys of East London (1969) 157: I bawled out at the top of my voice, ‘You dirty great cunt’.
1976		D. Ireland Glass Canoe (1982) 42: I forget I’m a policeman for an hour or two and polish off this dirty big meal.
1976		P. Theroux Family Arsenal 29: They’re trying to get some dirty great fridge off the pavement and not moving it an inch.
1982		G. Newbold Big Huey 80: He had a dirty big chisel strapped to his leg.
1985		B. Humphries Traveller’s Tool 33: With their dirty great aerosols in their hands.
1986		S. King It (1987) 293: If God is dirty-mean enough to curse the faithful with what they want most in life.
1996		Penguin Bk of More Aus. Jokes 437: A dirty great goat just came charging up behind me and threw itself down the mineshaft.
2000		Guardian Mag. 13 May 5: And those dirty great tattoos?

2. (US) illegally, in a criminal manner.

1988		T. Harris Silence of the Lambs (1991) 310: Justice says it’s a tricky case to make if we don’t catch him dirty.
1995		(con. 1985–90) P. Bourjois In Search of Respect 76: The only way you could survive in this world is to be [...] connected dirty. You got to be making your money dirty like the Eye-talians.
2001		N. Green Shooting Dr. Jack (2002) 156: ‘Drip test,’ she said. ‘He came up dirty.’.
2001		C. Stella Eddie’s World 206: He’d go dirty is my guess. He’d go underground. He’d go ethnic.