Green’s Dictionary of Slang

sit-down n.

1. (US tramp, also sit-downer) a free sit-down meal.

[US]Jackson & Hellyer Vocab. Criminal Sl. 56: Alas! Lumps are sometimes impaled on the fence pickets by fastidious beggars who become offended at the failure of well-meaning [...] philanthropists to invite them to eat at the table. This latter operation is gratefully termed a ‘sit-down.’.
[US]C. Samolar ‘Argot of the Vagabond’ in AS II:9 390: A sit-down is a meal in a private home, the hairpin having invited one in.
[US]Irwin Amer. Tramp and Und. Sl. 170: Sit Down. – A meal given a tramp within doors, at which he may sit down to a table and eat in comfort.
[UK]K. Mackenzie Living Rough 237: I got a sit-down from one woman [...] A couple of eggs and a sausage.
[US]O. Ferguson ‘Vocabulary for Lakes, [etc.]’ AS XIX:2 103: The word sit-down is familiar, as meaning you make a back door and the good lady asks you in to sit down for something hot in the kitchen.
[US]Goldin et al. DAUL 195/1: Sit-down. (Hobo) An invitation to come in and sit down to a meal.
[UK]B. Naughton Alfie Darling 138: It was a proper sit-downer with your feet under the table.
[US]Tyrone Dly Herald (PA) 19 Dec. 1/1: It [...] has now escalated to a sitdown free Christmas meal to which everyone alone is invited.
[Can](con. 1920s) O.D. Brooks Legs 179: I walked for two blocks before deciding to bum the lady of one of the houses for a handout, or a sit-down if I was lucky.

2. (US black) a rest.

[US]A. Bontemps God Sends Sun. 49: ‘Have some sit-down,’ Leah said. [Ibid.] 83: Ain’t you gonna ask me to come in an’ have some sit-down?
[US]C. Major Juba to Jive 210: Grab a sit down v. (1970s–1980s) take a seat; sit down.

3. (also sit) a conference.

[US]E. Torres Carlito’s Way 82: What are you going to say at the sitdown.
[US]H.C. Collins Street Gangs 224: Sit down Meeting to discuss important gang matters.
[US]Pileggi & Scorsese Goodfellas [film script] 54: Before you could touch a made guy [...] There had to be a sit-down.
[US]B. McCarthy Vice Cop 197: During one of Doug’s sit-downs with the burglar [...] they begin making plans for this art expert to come in on the deal.
[US]C. Stella Charlie Opera 3: You go out there for a asit-down with Lercasi, you gotta make like it’s a real-estate investment or some shit.
[US]C. Stella Charlie Opera 120: You could’ve asked for a sit with me. You should’ve asked for a sit with me.
[US]D. Winslow Winter of Frankie Machine (2007) 51: I’m going to come along for the sit-down, you don’t mind.
[US]Codella and Bennett Alphaville (2011) 14: He always dressed like he was going to a formal sit-down.
[US]C. Stella Joey Piss Pot 21: He was sent for by Fontana and a sit-down on Staten Island ensued.

SE in slang uses

In compounds

sit-down money (n.)

(Aus./US) unemployment benefit.

Cong. Record (US) 93:2 1555/2: Those sons are back home now trying to work. They are not asking for sitdown money, and the majority of them cannot go to college.
H.C. Coombs Kulinma 202: Community advisers became active in some communities in assisting Aborigines to apply for unemployment benefit ... generally Aborigines have been content to accept the ‘sitdown’ money without working [GAW4].
[Aus]Bulletin (Sydney) 10 July 77 n.p.: On every second Wednesday when the social security cheques – ‘sit-down money’ – are collected, the queues [for liquor] are much longer.
[Aus]Australian 17 Apr. 11: Aborigines call it ‘sit down money’ – the fortnightly payments from government for some form or other of welfare. They get it as of right, as do the aged, invalid and unemployed of all races and walks of life throughout Australia [GAW4].
[Aus]Age (Melbourne) 19 Dec. 15/7: I look forward to the day when ‘sit-down’ money no longer has any place in Australian culture.
sit-down stool (n.)

(US black) the buttocks.

[US]J.L. Gwaltney Drylongso 158: I warmed his sit-down-stool for starting all that who-shot-John.
sit-down-upons (n.)

trousers; the seat of the trousers.

[UK] New Mthly Mag. 513: I resolved to scale the palings, which I effected with some little damage from the splinters and tenterhooks to my sit down-upons .
[UK]Colburn's New Mthly Mag. III 106: Mary [...] threatened to lower his sit-down-upons and apply the rod to his epidermis.
Yankee Mag. 4 185/1: On handing it to the teacher, it was opened and said: ‘Missus — Whale the barer for runnin’ away’ [...] and the little fellow was accordingly admonished in the region of his ‘sit-down upons’.
[Aus]Bell’s Life in Sydney 15 Aug. 3/2: I experienced severe irritation extending downwards from the ‘sit down upon-part’ of that garment.