Green’s Dictionary of Slang

slash n.

1. an outside pocket [SE slash, a slit in a garment that is designed to reveal the colour of the lining].

[UK] ‘For I Will Prig For Ever’ in Flare-Up Songster 19: Again He’ll cut a dash, / At play, or prize ring act the swell, / And ease some spooney’s slash [...] Whilst Sally’s eye / Winks soft and sly, / He dings to her the cash.
[UK]H. Brandon Dict. of the Flash or Cant Lang. 165/1: Slash – outside coat pocket.
Manchester Wkly Times 23 Aug. 11/3: They assemble to share their spoils [...] the thimbles (watches) [...] from the pits (breast pockets) or slashes (outside coat pocket).
[US]Matsell Vocabulum.
[UK]Hotten Sl. Dict.
[Aus]Sydney Sl. Dict. (2 edn) 8: Slash - Outside coat-pocket.
[UK]Farmer & Henley Sl. and Its Analogues.

2. in context of urination [? SE slash, a thin, sloping line, i.e. that of urine; or echoic of the urine hitting the lavatory water].

(a) an act of urination.

[UK]K. Waterhouse Billy Liar (1962) 34: ‘Off for a slash,’ I muttered.
[UK]E. Bond Saved Scene x: Then ’e ’ops out an’ I ’as a little slash in ’is tea.
[UK]B.S. Johnson All Bull 63: He infuriated Bob by not having his slash on the way in.
[UK]W. Boyd On the Yankee Station (1982) 46: ‘Where are you going, Payne?’ Niles said tiredly. ‘For a slash, Niles.’.
[Aus]B. Humphries Traveller’s Tool 79: Every time a business colleague nicked off in mid T-bone through the swing door for a quick slash or a technicolour yawn.
[UK]M. Frayn Now You Know 40: Keep my shirt and socks on while I go [...] and have a slash.
[Aus]J. Byrell Lairs, Urgers & Coat-Tuggers xxii: The Flea was in the Leger brassco having a slash.
[Ire]P. Howard The Joy (2015) [ebook] [I] call one of the screws [...] to let me olut for a slash.
[Aus]M.B. ‘Chopper’ Read Chopper 4 18: Men [...] never wash their hands after a slash.
[UK]D. O’Donnell Locked Ward (2013) 247: He’s not in his farter [...] He’s takin’ a slash.
[Scot]G. Armstrong Young Team 137: A just want tae git tae a prtaloo fur a slash.

(b) urine.

[UK]B. Robinson Peculiar Memories of Thomas Penman 133: On the floor by the bed there was a bottle of slash that looked like orange juice from more than one country.
[UK]N. Griffiths Stump 185: You’d probly start drinkin yer own slash before the fuckin water ran out.

3. an alcoholic drink [DSUE suggests play on piss-up n.].

[UK]Partridge DSUE (8th edn) 1084/2: [...] since ca. 1930.
[US]Eble Campus Sl. Nov. 7: slash – small quantity of alcohol: Give me a slash of that beer.

4. (Aus./US) the vagina; thus slash stash, income from commercial sex[note Cleland, Memoirs of a Woman of Pleasure (1748–49): ‘The agreeable interior red of the sides of the orifice came into view, and with respect to the white that dazzl’d round it, give somewhat the idea of a pink-slash in the glossiest of white sattin’].

[[UK]Harris’s List of Covent-Garden Ladies 136: A lovely chestnut fringe, terminated by a pouting slash hole, which is far from being indefensible to the raptures of its grisly antagonist].
[US]Trimble 5000 Adult Sex Words and Phrases.
[US](con. 1968) Bunch & Cole Reckoning for Kings (1989) 279: Great fiancée with a pussy like a country club golf course [...] Got too busy with the slash, so they flunked my ass.
[Aus]B. Moore Lex. of Cadet Lang. 348: slash1 the vulva.
[Aus](con. 1964-65) B. Thorpe Sex and Thugs and Rock ’n’ Roll 133: That’s why he got 50 per cent of the slash stash.

In compounds