Green’s Dictionary of Slang

dag n.2

[dial. dag, a piece of matted wool and excrement clinging to a sheep’s tail; ? ult. SE dangle; cf. dags n.2 ]

1. (also daggy) in affectionate use, an appealingly eccentric person, a ‘character’, or thing; often ext. as real dag, bit of a dag.

[Aus]R. Thatcher Something to His Advantage 2: These are ‘Charley the Dag’, ‘Old Daddy’, the ‘Spring-heeled immigrant.’ [AND].
[Aus]Truth (Melbourne) 10 June 1/4: The chinkss Ioat who sucks a half-smoked fag, / Finds favor in her sight; with rakish air / He claims to be regarded as a "dag" / (The latest slang for manners debonnair [sic]).
[Aus]E.G. Murphy ‘Mrs. Flanagan’s Frock’ in Dryblower’s Verses 71: ‘And what,’ asked the Warden, ‘are you seeking there?’ / Of a dag who from flounces was taking his fill.
[UK]J. Campbell Babe Is Wise 205: Then I know w’at it is . . . you’re a dag with a skirt.
[NZ]F. Sargeson ‘A Pair of Socks’ in A Man and His Wife (1944) 64: Struth, he was a dag.
[UK]D. Davin For the Rest of Our Lives 373: He seems to have been a bit of a dag, this joker.
Record Hackensack (NJ) 8 Sept. 45/2: [In] a special section of Australian slang I learned [...] that instead of being a ‘dabster’ (expert) I am only a ‘dag’ (humorous fellow) who is ‘giving a fly’ (making an attempt) at talking ‘fodder’ (nonsense) [...] I assure you that this is all ‘square dinkum’.
[Aus]D. O’Grady A Bottle of Sandwiches 68: He was a bit of a dag, the old Bern. Always ready with a quick quip and a witty answer.
[NZ]J. Henderson Exiles of Asbestos Cottage 38: A watch which had belonged to his father in France. The hands went anti-clockwise. [...] ‘A dag of a watch.’.
[Aus]C. Bowles G’DAY 98: If a person is [...] a clown, they’re a bit of a dag.
[NZ]McGill Dict. of Kiwi Sl. 34/1: dag, daggy amusing person or thing, memorably in Fred Dagg, rural comic creation of urban Kiwi John Clarke in 1970s, dressed in black woollen farmer’s singlet, muddy shorts and gumboots, an apparently dim but actually canny cocky; exported to Australia, whence word originated c.1890.
[Aus]T. Winton Human Torpedo 53: Hypodermical! Geez, yer a dag!
[Aus]R.G. Barrett Mystery Bay Blues 290: Hello Morticia, you little dag.
[NZ]McGill Reed Dict. of N.Z. Sl. [as cit. 1988].
[Aus]L. Redhead Peepshow [ebook] Me, cool? I’d always thought I was a bit of a dag.

2. an unenterprising person, a coward.

[NZ]G. Slatter Gun in My Hand 45: But you’re a dag, you are. What’s biting ya? Ya’d never rush outa the boozer in the old days.
[Aus]B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 78: Let’s shoot through before the dag yells for the blues.
[Aus]T. Winton That Eye, The Sky 35: The two yobbos just stand there and look like dags.
[Aus]S. Maloney Sucked In 137: As big a pack of dags and busybodies as you could ever hope to assemble.
[UK]Guardian CiF 14 Dec. [Internet] Picture of political dag with snag.

3. an unfashionable dresser.

[UK]K. Lette Llama Parlour 36: The maître d’ bloke slipped a surreptitious glance at my faded jeans and perished T-shirt, trying to ascertain if I was just a common old dag, too poor to afford good clothes, or so rich and famous I didn’t give damn what I wore.