Green’s Dictionary of Slang

attaboy! excl.

also at-a-boy! attababes! attababy! attagirl! atta kid! thataboy! thatta baby! thatta boy!
[? phr. ‘that’s the boy’ etc or ‘at her, boy’ (DSUE), where ‘her’ is neuter. Note US milit./police jargon attaboy, a commendation; Fraser & Gibbons, Soldier & Sailor Words & Phrases (1925), suggest it is ‘American slang used by players and lookers on at Base-ball matches’]

(orig. US) a general excl. of admiration and encouragement.

[UK]Cornhill Mag. CIL 149: The Emir [...] rushed from the tent, with a low exhortation of ' Attaboy, Bud! Bust him up!
[US]Foundry L 331/3: Attaboy, but keep your nose off the grindstone.
[US]Amer. Mag. May 40/2: Back of Chance’s war cries, ‘At-a-boy’, or ‘Now ye’re pitching’, may be hidden a whole command to his team .
[US]Van Loan ‘No Business’ in Taking the Count 167: A glove thudded [...] into the unarmored region known as the pit of the stomach. ‘Thatta boy!’ howled the Cricket. ‘Downstairs!’.
[US]R. Lardner ‘Alibi Ike’ in Coll. Short Stories (1941) 49: ‘Yatta boy!’ says Carey. ‘Congratulations!’.
[US]Wash. Times (DC) 19 Mar. 14/2: Thattaboy! Thattaboy!
[US]Topeka State Jrnl (KS) 19 Apr. 8/3: Yah-ha! Attaboy! Attaboy! Pitch to me kid — put her there!
[US]N.Y. Tribune 6 Aug. 5/4: ‘Attagirl!’ Camille Sabie [...] hurdler of the track team.
[US]H.C. Witwer Fighting Blood 42: ‘Attaboy!’ says Spence, slapping the counter.
[US]Dos Passos Manhattan Transfer 311: Now give me a real kiss sweetest. Thataboy.
[US]G.S. Schuyler Yellow Peril in Hatch & Hamalian Lost Plays of Harlem Renaissance (1996) 58: More hooch, eh? Atta baby!
[US]M. West Sex (1997) I ii: Wrap yourself around this. Atta girl.
[US]C. Coe Hooch! 194: ‘Thatta baby,’ Flenger grunted.
[US]J. Lait Broadway Melody 40: ‘I’m just — s-so h-h-happ-ppy!’ ‘Attababes.’.
[US]W.R. Burnett Iron Man 227: Atta boy, Coke [...] Give ’em what they end, kid.
[US](con. 1920s) J.T. Farrell Young Manhood in Studs Lonigan (1936) 369: ‘Thataboy, Studs,’ said Phil Rolfe.
[US]H. Roth Call It Sleep (1977) 344: Atta kid! Aintchoo goin’ dough [...] Atta kid!
[UK]Peters & Sklar Stevedore II iii: Atta girl, sugar! Hot mama!
[US]J.M. Cain Mildred Pierce (1985) 376: ’Atta girl!
[UK]G. Fairlie Bulldog Drummond Stands Fast 33: ‘Attagirl!’ said Algy.
[US]B. Schulberg Harder They Fall (1971) 205: Attaboy, cut him down to your size!
[US]F. Brown Dead Ringer 109: ‘Attababy,’ I said.
[US]M. Spillane One Lonely Night 28: Attaboy, buddy!
[US]S. Sterling ‘The Kiss and Tell Murders’ Popular Detective May 🌐 ‘Okay. Two Fundador, right away.’ ‘Attakeed.’.
[US]F. Kohner Affairs of Gidget 112: ‘Atta girl!’ yelled Ollie.
[US]P. Thomas Down These Mean Streets (1970) 232: ‘This is a stick-up.’ His voice sounded like bombs falling. Attaboy, Danny.
[US]J. Roe The Same Old Grind 118: ‘Atta girl,’ said Max.
[US]A. Maupin Tales of the City (1984) 197: ‘Attaboy!’ said Herbert Tolliver.
[UK]S. Berkoff Decadence in Decadence and Other Plays (1985) 10: Attagirl / that’s how I like to see you chat.
[US]C. Heath A-Team 2 (1984) 155: ‘Atta boy, Driver!’ one of his companions rooted.
[US]‘Heat Moon’ Blue Highways 154: Loud and cocky, he cried out, ‘Attabaybee!’.
[UK]K. Lette Mad Cows 67: ‘Atta girl!’ Mamma Joy enthused.
[UK]Indep. Rev. 6 July 2: Attaboy. Good luck.
[Ind]S. Varma Lament of Mohini 18: Atta boy, that’s it, you’re doing fine, go to it!
[US]S. King Finders Keepers (2016) 15: ‘I would like a little support here.’ ‘Maybe even an attaboy.’ ‘Atta-baby,’Tom said.