Green’s Dictionary of Slang

1. a lark, a game; crime.

1891		G.R. Sims ‘Tottie’ Dagonet Ditties 127: (She cried, ‘What a Noah’s ark!’), / And right through my ‘rank and riches’ / Did my ‘cribbage-pegs’ assail.
1964		H. Williams Speakers (1966) 171: .

2. a lark (the bird).

1937–84

Partridge DSUE (1984) 798: 1887.

3. a park.

1924		G.H. Lawson Dict. of Aus. Words And Terms 🌐 NOAH’S ARK—A park.
1935		A.J. Pollock Und. Speaks.
1944		Maurer & Baker ‘“Aus.” Rhyming Argot’ in AS XIX:3.
1960		J. Franklyn Dict. of Rhy. Sl.
1971		J. Jones Rhy. Cockney Sl.
1983		R. Aven-Bray Ridgey-Didge Oz Jack Lang 37: Noahs Ark Park.
2002		B. Kirkpatrick Wicked Cockney Rhy. Sl.

4. an informer [= nark n.¹ (1)].

1914		E. Dyson Spats’ Fact’ry (1922) 72: ‘Ga-art, Feathers, don’t be a Noah’s Ark!’ Nicholas was showing some trepidation. ‘A nark — me?’ ejaculated Mills virtuously.
c.1921		T. Norman Penny Showman 5: I was what they called a Noah’s Ark (Nark).
1941		V. Davis Phenomena in Crime 254: A stoolie, Noah’s ark, a grasshopper. A nark or informer.
[1947		Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks 7: Noah’s ark or nark: To watch or look out].
1960		J. Franklyn Dict. of Rhy. Sl.
1971		J. Jones Rhy. Cockney Sl.
1982		G. Newbold Big Huey 251: noah’s ark (n) Informant.
1999		G. Seal Lingo 90: Since the late 19th century criminal argot has also used noah’s ark to mean narc, an informer.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 124/2: Noah’s ark n. an informer.
2002		B. Kirkpatrick Wicked Cockney Rhy. Sl.

5. (Aus.) a dullard, a fool [= nark n.¹ (4)].

1900		Bulletin (Sydney) 24 Mar. 32/1: ‘Pa only owns a newspaper office there.’ / ‘Have they any Noah’s Arks there?’ enquired the youngest boy, who was always on business bent. / And of course, the Writer had to reply that the Noah’s Arks, and the wooden patriarchs who came out of them, could only be found in the Sydney Morning Herald office.
1941		Baker Popular Dict. Aus. Sl. 49: A Noah’s ark, a dull, witless fellow. A rhyme on ‘nark’.
1968		J. Alard He who Shoots Last 97: Ya knows Bill, yer gettin’ ta be a real Noah’s Ark.

6. (Aus.) a shark.

1963–74		B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 102: A lotta them beaches in Oz are full of Noahs.
1968		D. O’Grady A Bottle of Sandwiches 114: I didn’t and don’t trust Noah’s arks of any size.
1985		B. Humphries Traveller’s Tool 13: Some whizz kids have even determined that Harold Holt wasn’t sucked off a rock by a Noah.
1997		T. Winton Lockie Leonard, Legend (1998) 5: Hooley-dooley, that was no dolphin. [...] It was a Noah’s ark.
2001		Observer Sport Monthly 2 Dec. 34: ‘That’s the toughest little bugger in the ocean. Except Noahs.’ ‘Noahs?’ ‘Arks. Sharks.’.
2016		N. Cummins Adventures of the Honey Badger [ebook] We must have hooked up on [to a fish] at least 20 occasions but every time they were snaked by a Noah.
2021		Betoota-isms 248: ‘[S]wear I spotted a few Noah’s Arks out on the reef’.

7. a prostitute [unusual in that it rhymes on the first word, Noah’s = [wh]’ores, in a Cockney pron.].

1953

J. Franklyn Cockney 294: To refer to her as a Noah’s Ark means the same thing; and in this the rhyme, which is also a pun, and would not fit any but cockney dialect, falls on the first element.

8. (Aus.) a moneylender [= shark n. (3a)].

1967

‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxvi 4/2: noah’s ark: Shark. Applied also to moneylenders.

9. a heckler.

1964

H. Williams Speakers (1966) 171: A Noah’s Ark, that’s a nuisance in the crowd . . . Noah’s Ark, Hude Park, it goes on from there, to rhyme, until you get to heckler.