Green’s Dictionary of Slang

nelly n.

1. (Aus.) cheap wine.

1945		Baker Aus. Lang. 166: Here is a group of indigenous terms used to describe cheap wines: [...] ink, lunatic soup, nelly, nelly’s death, paint.
1955		N. Pulliam I Travelled a Lonely Land (1957) 236/1: nellie (nelly, nellie’s death, nellie’s downfall) – cheap wine.
1967		A.E. Debenham All Manner of People 84: There was some money left over, so they spent that [...] on cheap wine (better known as ‘plonk’, ‘Nellie’, or ‘fourpenny dark’) [AND].
1972		A. Chipper Aussie Swearers Guide 67: Wine fanciers of all descriptions leave themselves open to being called plonk fiends or plonkos. (refer scornfully to their [...] nelly or fourpenny dark).
1980		(ref. to 1920s–30s) Hepworth & Hindle Boozing out in Melbourne Pubs 15: Affectionate nicknames for the stuff itself were: scarlet runner, [...] nelly, pinky, plonk and plink.
1983		R. Aven-Bray Ridgey-Didge Oz Jack Lang 37: Nelly Wine.

2. (Aus.) semen.

1979

Lette & Carey Puberty Blues 44: Small gang-bang, eh [...] Nelly come out ’er mowf.

In compounds

Nelly-law (n.)

(N.Z. camp gay) a police officer, usu. male.

2010

(con. 1960s) W. Ings ‘Trolling the Beat to Working the Soob’ in Int’l Jrnl Lexicog. 23:1 72: In the early 1960s in New Zealand Vivian Vice, Nelly-law, Dolly Handbag, Alice, Dora-D, Hilda-Handcuff, Lily-lunchbox, Jennifer-Justice, Hilda Box-rot, Petunia Pig, Tilly Tight-twat, and Cherie Cunstable, were familiar.