Green’s Dictionary of Slang

1. a hill.

1934		John O’London’s Weekly 9 June in DSUE (1984).
1960		J. Franklyn Dict. of Rhy. Sl. 81/1: Jack and Jill (2) hill seems to have been evolved after 1918, and is sometimes applied to the stairs since they are frquently called the wooden-hill.
1971		J. Jones Rhy. Cockney Sl.
2002		M. Coles More Bible in Cockney 12: Get yourselves up to the top of a bloomin’ Jack-and-Jill. [Ibid.] 23: Me and me currant are off up that Jack over there to worship God.

2. a bill.

1932		‘P.P.’ Rhy. Sl. 7: Put yer ‘mince’ over the ‘Jack and Jill’.
1962		F. Norman Guntz 31: I paid the jack and jill and we left.
1971		J. Jones Rhy. Cockney Sl.
1983		A. Payne ‘Get Daley!’ Minder [TV script] 10: I come in here, traumatised, for a medicinal brandy and you can’t wait to slip me the jack and jill!
2005		P. Howard Curious Incident of the Dog in the Nightdress 24: The old Jack and Jill is proving to be a bit of an issue with the management.

3. a till.

1935		A.J. Pollock Und. Speaks.
1943		Western Dly Press 21 Apr. 2/5: 'Jack and Jill' is Cockney rhyming slang for a till - a shopkeeper's till.
1944		Maurer & Baker ‘“Aus.” Rhyming Argot’ in AS XIX:3.
1959		J. Gosling Ghost Squad 24: Thieves’ argot, spoken properly, is a foreign language which needs to be learned [...] Among the words and phrases derived from rhyming slang are: [...] Jack and Jill (till).
1969		S.T. Kendall Up the Frog.
1971		J. Jones Rhy. Cockney Sl.
1983		R. Aven-Bray Ridgey-Didge Oz Jack Lang 32: Jack and Jill Till (cash register).
1989		in G. Tremlett Little Legs 195: jack a till (abb. for Jack and Jill).
2002		B. Kirkpatrick Wicked Cockney Rhy. Sl.

4. a pill, esp. of heroin; usu. in pl; also note cite 2001.

1961		T. Taylor Baron’s Court All Change (2011) 71: His works were neatly arranged [...] complete with spoon and a candle stuck to a saucer to heat his jacks up with.
1967		Oz 2 13/1: She will sell heroin at ¾d. a jack or £1 a grain.
1980		S. McConville ‘Prison Language’ in Michaels & Ricks (1980) 526: Heroin [is] jack.
1988		J. Healy Grass Arena (1990) 118: When somebody pulls out the Jack and Jills – you take a few, of course.
1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Jack and Jill. Rhyming slang for pill, specifically amphetamines.
1993		I. Welsh Trainspotting 204: Thair oan that pure pharmaceutical shite while we’re reduced tae crushin up any fuckin jack n jills we kin git oor hands on.
2000		J.J. Connolly Layer Cake 121: Lucid dreams about [...] this afternoon’s disappointment over the Jack and Jills.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 94/1: jack-and-jill n. a pill: ‘I wouldn’t mind seeing jack-and-jill [...] jack is a barbiturate [...] jill, on the other hand, is an amphetamine, or 'upper',.
2010		K. Richards Life 200: He used to keep spare jacks, a sixth of a grain - it was six jacks to a grain of heroin - loose in these suit pockets.

5. (Aus.) a fool [= dill n.¹ ].

1971		J. McNeill Chocolate Frog (1973) 23: Tosser: [H]e’s just a jack ’n jill!
2002		Pete’s Aussie Sl. Home Page 🌐 Jack and Jill (1): a dill, a fool .

6. a contraceptive pill.

2012

(con. 1980s) I. Welsh Skagboys 145: Wishin that the lassie had gied her hole tae anybody but Franco or hud swallayed the auld jack n Jill wi her cup ay English Breakfast.