Green’s Dictionary of Slang

treacle n.

1. inferior port.

[UK]Farmer & Henley Sl. and Its Analogues.
[UK]Partridge DSUE (1984) 1261/2: from a.1780.

2. glutinously sentimental love-making.

[UK]Farmer & Henley Sl. and Its Analogues.
[Ire]P. Boyle All Looks Yellow to the Jaundiced Eye 105: You would imagine that anyone could squeeze a bit of feeling out of ‘Charmaine’- a number oozing with treacle.

3. (UK Und.) bribe money [+ play on sweeten v. (2)].

[UK]Leaves from Diary of Celebrated Burglar 126/2: ’E’s skweezed ennuff ‘treacle’ eowt on uz areddy, t’ long ’ound, an’ wi nevvir got awt by ’t.

4. (Aus. drugs) opium.

[Aus]H. Nisbet ‘Bail Up!’ 219: Now, wire along, johnny, with the treacle.
[Aus]Truth (Brisbane) 28 Oct. 13/2: [pic. caption] These containers of ‘treacle’ — as the dope is termed in slang — are bought by smugglers from the Orient.

5. insincere, empty talk, typically that of a politician.

[UK] ‘’Arry on Niggers’ in Punch 15 Mar. 113/2: They’ll talk any treacle to choke our brave chaps off a jolly good fight.
[UK] ‘’Arry at a Political Pic-Nic’ in Punch 11 Oct. 180/1: The palaver was sawdust and treacle.
[UK] ‘’Arry on Blues and Bluestockings’ in Punch 21 Mar. 135/1: We’re a deal too much petticoat governed, a rule that means treacle and pap.
[Aus]Sun. Times (Perth) 2 June 1/1: In anticipation of the Eastern job, he bought a new coat [but] the billet fell to someone else who couldn’t even tell treacle tales.
[US]T. Wolfe Web and the Rock 530: Compared to all the seven hundred and ninety-six varieties of piffle, treacle, bilge, quack-salvery and hocus-pocus.

SE in slang uses

In compounds

treacle-man (n.) [the stickiness and sweetness of SE treacle]

1. a good-looking man who works as a decoy for burglars by charming the housemaid while the gang slip in unnoticed.

[UK]J. Ware Passing Eng. of the Victorian Era 249/2: Treacle-man (Thieves’). Beautiful male decoy who is the pretended young man of the housemaid and the real forerunner of the burglar. [...] Often used to designate the commercial traveller who has to make sales of type-writers, sewing machines, etc. to young girls and old women. Sometimes bitterly applied by drapers’ assistants to any one of their number who makes the smartest sales.

2. a smooth-talking, good-looking travelling salesman, who uses his charms to persuade the ‘lady of the house’ to buy his wares.

see sense 1.

3. a shop assistant, esp. in a draper’s, who has the same effect on customers.

see sense 1.
treacle-miner (n.)

(Aus.) a man who boasts of his wealth or position.

[Aus]W.H. Downing Digger Dialects 50: treacle-miner — A man who boasts of his wealth in Australia or his position in private life.
[Aus](con. WWI) A.G. Pretty Gloss. Sl. [...] in the A.I.F. 1921–1924 (rev. t/s) n.p.: treacle miner. A man who boasts of his wealth in Australia or his position in private life.
treacle plaster (n.)

(UK Und.) a sticky piece of brown paper used by a thief to remove glass carefully; also as a form of gag.

[UK]E. Jervis 25 Years in Six Prisons 97: There was George Gordon, of the ‘treacle-plaster’ case [...] The cashier had gone through the first part of the subway. They then pressed a piece of paper covered with treacle or birdlime over his mouth to prevent his crying out.
[UK]N. Lucas London and its Criminals 241: A ‘treacle plaster,’ which comprises a piece of brown paper smeared with some sticky substance for pasting on a window. A circle is then cut round with a glass cutter and the glass prevented from falling – and raising the alarm – by the ‘treacle plaster.’.
[UK]R.T. Hopkins Life and Death at the Old Bailey 64: In a burglar’s kit of tools will be found [...] a ‘treacle plaster’ – the last a piece of brown paper smeared with bird-lime.
treacle sleep (n.) [the slow pouring of thick SE treacle]

deep, uninterrupted sleep.

T. Carlyle in Froude Life in London (1884) 210: In spite of noisy servants, in spite of all things, I fell first into a sluggish torpor, then into treacle-sleep, and so lay sound as a stone.
treacle stick (n.) [? link to practice seen in Dickens’ Nicholas Nickleby (1839) where brimstone and treacle is used to dose poor children and reduce their appetite for anything else]

(UK und.) a relieving officer; parish relief.

[UK]Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks 11: Treacle stick: Relieving officer or parish relief.

In exclamations

treacle(-trousers)! (also treacle pants) [? they stick to the wearer’s legs]

(Aus.) trousers that are too short fo the legs and thus used as a jibe aimed at one whose trousers are too short.

[Aus]Sydney Sportsman (Surry Hills, NSW) 17 Oct. 2/2: [He] played the wicked baronet dressed in a biillycock hat, ‘treacle’ pants, and a macintosh.
[Aus]Narracan Shire Advocate (Vic.) 12 Oct. 3/3: Mr Monty aroused much laughter by his antics as ‘Tommy Treacle-trousers,’ the ‘hard case’ of the school.
E.H. Burgmann Educ. Aus. 23: I was growing fast, and as a gap between the top of my boots and the bottom of the legs of my trousers appeared slightly greater day by day, I was greeted by the cry of ‘treacle.’ [AND].