Green’s Dictionary of Slang

1. a penny.

1854		Leicester Jrnl 28 Apr. 4/2: The boy followed up his information by a request for a ‘yennep’ to get a ‘tib of occabot’.
1856		H. Mayhew Great World of London I 5: I’ve been doing b----y dab (bad) with my tol (lot, or stock) — ha’n’t made a yennep (penny), s’elp me.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor I 472/1: All a fellow wants to know to sell potatoes [...] is to tell how many tanners make a bob, and how many yenaps a tanner.
1873		N.S. Dodge ‘Vagrants and Vagrancy’ in Appleton’s Journal (N.Y.) 6 Sept. 308/1: Vagrant vernacular [...] is not remarkable for originality, and, unlike most low languages, possesses no spice of humor. The main principle upon which this peculiarity revolves, is to spell and pronounce the substantives in any sentence backward. Yennep, in this way, stands for penny.
1876		Leeds Times (Yorks.) 5 Feb.7/5: Matey [...] d’ye ’appen to have a yennep (penny) more’n you want?
1881		Morn. Bulletin (Rockhampton, Qld) 18 July 2/6: For a penny (English) and doit (Scotch) wc have only thc names ‘saltee,’ ‘winn,’ and ‘yenep’.
1890		Northampton Mercury 12 Apr. n.p.: ‘Yennep,’ a penny [...] ‘flatch,’ a halfpenny.
1896		A. Morrison Child of the Jago (1982) 50: Where’s the yannups come from wot’s bin for to pay the rent, an’ git the toke.
1909		J. Ware Passing Eng. of the Victorian Era 29/2: We have been awfully stoney in our birdlime, and didn’t know where to turn for a yannep, so we’ve had to fill up our insides on something less than two quid a week.
1911		J.W. Horsley Memoirs of a ‘Sky Pilot’ 252: Rhyming slang and back slang, invented and chiefly used by costermongers, to whom, ‘daisy roots’ is a substitute for the word boots, and ‘yennep’ for a penny.
1923		Eve. Teleg. (Angus, Scot.) 11 July 11/4: For example, top for pot, yennep for penny, nig for gin, and nodol for London.
1935		R.T. Hopkins Life and Death at the Old Bailey 65: Costermongers invariably use the following terms in discussing money transactions [...] Yenep – Penny.
1953		J. Franklyn Cockney 297: Yenep is a ‘penny.’.
1977		D. Powis Signs of Crime 207: Yennap A penny (London backslang).

2. in fig. use of sense 1, something / someone valueless.

1837

‘Now!’ in Rum Ti Tum! in Spedding & Watt (eds) Bawdy Songbooks (2011) III 170: And has for that lop-sided Joe — / He’s nothing but a yawnips.

3. (Aus. und.) in pl., petty theft, begging, pickpocketing.

1902

Truth (Brisbane) 23 Feb. 3/5: Three long years is fairish schoolin' / [...] / For 2 learn the game of ‘yannops,’ / Witch are slang fur theevin’ sport.