Green’s Dictionary of Slang

earth yenneps n.

three pence.

1859		Hotten Dict. of Modern Sl. etc. 126: EARTH YANOPS, or yeneps [...] ERTH-YENEPS, threepence.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor I 23/1: Erth-yenep ... Threepence.
1867		Berks. Chron. 7 Dec. 7/1: The language of Costers. We’ve a slang, sir, and it is only know to ourselves. It puzzles the Irish and bothers the Jews [...] We say yenep for penny, erth-yenep for three pece, neves yenep, for seven-pence.
1873		N.S. Dodge ‘Vagrants and Vagrancy’ in Appleton’s Journal (N.Y.) 6 Sept. 308: 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; owt-yeneps, for twopence; erth-yeneps, for threepence; rouf-yeneps, for fourpence, and so on.
1892		Lloyd's Wkly Newspaper 3 Jan. 6/5: Here's erth-yeneps [...] and I wish it were erth-gens.
1935		R.T. Hopkins Life and Death at the Old Bailey 65: Costermongers invariably use the following terms in discussing money transactions [...] Erth-yenep – Threepence.
2001		J. Burkardt ‘Back Sl.’ Wordplay 🌐 erf yennep: threepence.