Green’s Dictionary of Slang

not give a damn v.

also not care a damn, not give/care a black damn, ...a dam, ...a D, ...a darn, ...a dern, ...a domn, ...a doodley damn, ...a drat, ...a durn, ...a good damn, ...a nigger’s damn
[damn n., but note Hind. दाम (dām) a coin of infinitesimal value (1/25 of a paise), दमड़ी (damṛī) a coin of small value (1/4 or 1/8 of a paise)]

to not care at all.

[UK]Grose Classical Dict. of the Vulgar Tongue n.p.: Dam, a small Indian coin, mentioned in the Gentoo code of laws: hence etymologists may, if they please, derive the common expression, I do not care a dam, i.e. I do not care half a farthing for it.
[UK]‘Peter Pindar’ ‘Pindariana’ Works (1796) IV 224: Who gives my sweet civility a d-mn.
[UK]Last Act in New British Theatre II i: I do not care a d--n.
[WI]M. Lewis 26 Mar. in Journal of a West India Proprietor (1834) 233: Hey-ho-day! me no care a dammee!
[Ire]‘A Real Paddy’ Real Life in Ireland 276: Dear Gram, – I don’t care a D--n, / If your letter is only a soldier’s Flam.
[UK]Bell’s Life in London 9 Feb. 2/5: For the whole Beaks in England I don’t care a damn.
[US]N.Y. Transcript 15 Feb. 2/4: She did not care a d—n if they had sent her up for forty-eleven years.
[US]W.T. Porter Big Bear of Arkansas (1847) 119: The bar don’t care a dam for nobody!
[UK]M. Reid Scalp-Hunters II 277: ‘Wagh! what cares he for us, now that he has got what he wanted?’ ‘Not a niggur’s d--n.’.
[US]C. Abbey diary 19 Nov. in Gosnell Before the Mast (1989) 153: Don’t care a Darn.
[Aus]Bell’s Life in Sydney 10 Sept. 3/2: A bluff, yeoman-like man, with a ‘don’t care a d— for nobody’ appearance.
[UK]Leaves from Diary of Celebrated Burglar 18/2: Jack replied that he did not care a — how tough it was.
[US]C.G. Leland ‘Breitmann in Battle’ in Hans Breitmann’s Party 5: ‘Away down Sout’ in Tixey dey’ll split you like a clam’ — / ‘For dat,’ spoke out der Breitmann, ‘I doos not gare one tam’.
[US] in G. Legman Limerick (1953) 294: Cuss it, I don’t give a damn.
[US]C. White ‘The Darkey’s Stratagem’ Act I: I don’t care a darn if you never come back.
[US](con. c.1840) ‘Mark Twain’ Tom Sawyer 272: I don’t give a dern for a thing ’thout it’s tollable hard to git.
[US]‘Mark Twain’ Life on the Mississippi (1914) 393: It’s [...] human nature in grief. It don’t reason, you see. Time being, it don’t care a dam.
[UK]Ally Sloper’s Half Holiday 14 June 50/2: [caption] A Stroll down the strans-ity / stick ion the hand-ity / Dpn’t care a d—ity fellow.
[US] in Overland Monthly (CA) July 68: He didunt keer a darn fur the flag.
[US] Willard Thompson ‘Razzle Dazzle’ [lyrics] Nobody knows when we’re out upon a spree, nobody knows nor cares a D.
[UK]‘Walter’ My Secret Life (1966) IX 1848: I like it, I don’t care a damn who knows it.
[UK]Sporting Times 22 Feb. 2/3: Nobody caring a tuppeny dam for law and order.
[UK]Kipling ‘Fuzzy-Wuzzy’ in Barrack-Room Ballads (1893) 152: ’E’s the only thing that doesn’t give a damn / For a Regiment o’ British Infantree!
[US]J. Frye Fables of Field and Staff 51: The boy who cares not one darn whether school keeps or not.
[US]H. Blossom Checkers 129: I do n’t know, and, what’s more, I do n’t care a damn.
[UK]Binstead & Wells Pink ’Un and Pelican 270: I wouldn’t mind a damn for meself, sir, but I’ve got my bit o’ trouble at home.
[US]Flynt & Walton Powers That Prey 21: I don’t give a damn whether he does or not.
[UK]A. Binstead Pitcher in Paradise 192: I don’t care a damn what anybody says.
[Aus]J. Furphy Such is Life 9: He don’t give a dam.
[UK]Sporting Times 18 Mar. 1/2: The L.C.C. has struck another three halfpence on to our taxes. Three halfpence may not seem much, but the amount the L.C.C. care is a good deal less. They don’t care one d.
[US]W.M. Raine Bucky O’Connor (1910) 91: I don’t give a domn whether Megales or Valdez is governor.
[Ire]Joyce Portrait of the Artist as a Young Man 234: I don’t care a damn about you, Cranly, answered Temple.
[UK]Wodehouse ‘Extricating Young Gussie’ in Man with Two Left Feet 25: You don’t give a darn whether you see the needle or not.
[UK]‘Sapper’ Human Touch 97: I don’t give a dam for the Boche numbers.
[Aus]W.H. Downing Digger Dialects 20: don’t give a damn —Dont’ care.
Appleton (Wisc.) Daily Post 6 Jan. 5/6–7: [advert] Buckaroo (buck-a-roo) [...] Meaning, when applied to the masculine gender of the human species, a lively young buck. 2. A gay dog. One who doesn’t give a darn.
[US]F.S. Fitzgerald ‘The Jelly Bean’ in Bodley Head Scott Fitzgerald V (1963) 218: I don’t guess Nancy cared a darn about him.
[UK]‘Sapper’ Bulldog Drummond 37: Hugh Drummond admitted to himself [...] that he didn’t care a damn if it was (i.e. a hoax].
[US]Van Vechten Nigger Heaven 39: I don’t give a damn where you go, just so you get out of here.
[US]C. McKay Banjo 125: I don’t care a black damn whose it is.
[US]D. Parker ‘Here We Are’ in Parker (1943) 35: I don’t give a darn what they cost.
[UK]G. Greene Gun for Sale (1973) 17: I don’t care a damn if I shoot you.
[UK]P. Cheyney Dames Don’t Care (1960) 46: Nobody gave a durn about whether granworth Aymes committed suicide or not.
[Aus]K. Tennant Battlers 110: ‘Not that I care a damn,’ he added hastily.
[US]M. Curtiss Letters Home (1944) 299: He didn’t give a happy dam.
[US]M. Spillane One Lonely Night 144: I didn’t give a good damn one way or another.
[US] in E. Cray Erotic Muse (1992) 91: I do not give a darn. / Guilty in the first degree! To the penitentiary!
[US]H.S. Thompson letter 12 Dec. in Proud Highway (1997) 79: They don’t give a damn if the headlines make any sense or not.
[US]E. Gilbert Vice Trap 121: He doesn’t give a doodleydamn.
[UK]E. Bond Saved Scene v: It’s father don’t give a damn.
[US]N. Heard Howard Street 53: When Mr Anderson fired me, I just smiled [...] and walked out. I didn’t give a damn.
[NZ]R. Morrieson Pallet on the Floor 102: I got reason not to give a dam.
[UK]P. Theroux Picture Palace 172: He doesn’t care a damn about her.
[UK]P. Theroux London Embassy 130: Cats don’t give a damn.
[Aus](con. 1940s–60s) Hogbotel & ffuckes ‘The Old Maid’ in More Snatches and Lays 87: She didn’t give a drat for the old tom cat.
[Aus]T. Winton That Eye, The Sky 22: You never cared a black damn for her.
[US]P. Califia Macho Sluts 38: I don’t give a damn what they think.
[US] Tarantino & Avery Pulp Fiction [film script] 79: I don’t give a damn what men find attractive.
[UK]C. Dexter Remorseful Day (2000) 12: ‘You know you just said you didn’t give a dam. Do you know how you spell “dam?”’ ‘You spell it “d – a – m”. Tiny Indian coin – that’s what a dam is.’.
[UK]Sun. Times Mag. 6 Feb. 27: This new bunch are dirty – they defecate in camps – do hard drugs, don’t give a damn.

In phrases

don’t-give-a-damn (adj.) (also don’t-care-a-dam(n), don’t-give-a-shit)

(US) careless, carefree; also as n.; thus don’t-give-a-damnism n.

[Aus]C.J. Dennis ‘The Game’ in Moods of Ginger Mick 111: The willin’est, the cheeriest, don’-care-a-damest crowd.
[US]B. Cormack Racket Act II: That’s your way – in the dark, so’s you can hide, and frame, and fix, and grab, till everybody’s rotten with fear and don’t-give-a-damn, and a man can’t call his soul his own.
[US]M. West Pleasure Man (1997) Act I: For instance, young Miss don’t-give-a-damn, why were you so anxious to take this particular engagement?
[UK]G. Gibson Enemy Coast Ahead (1955) 266: Most of them wore expressions varying from the ‘don’t care a damn’ to the grim and determined.
[US]W. Motley Knock on Any Door 485: He pulled away roughly. ‘Cut it out, Ma!’ And he was sorry he said it, hard-boiled and don’t-give-a-damn.
[US]J. Rechy City of Night 25: Then he walks by me, Hat slouched to one side, don’t-give-a-damn walk.
[US]M.S. Brookins ‘Aspiration’ in Kochman Rappin’ and Stylin’ Out (1972) 381–2: The warm glow of the wine was now leaving the pit of my gut and slowly, pleasantly rising upward toward my head, where it would envelop my brain with that wonderful feeling of don’t-give-a-damnism.
[UK]J.J. Connolly Layer Cake 8: It’s a I-don’t-give-a-shit attitude like you’d have to kill the fuckers to stop them coming at you.
[UK]Indep. on Sun. Real Life 23 Jan. 3: Model Trish Goff has brought her don’t-give-a-damn ‘do onto the catwalk.