Green’s Dictionary of Slang

bread-and-butter adj.

[the blandness of the food]

1. childish, juvenile, esp. schoolgirlish, often as bread-and-butter miss, a (deliberately) childish young woman.

[US]Irving & Paulding Salmagundi (1860) 214: These little, beardless, bread-and-butter politicians, who, on this occasion, escape from the jurisdiction of their mammas to attend to the affairs of the nation.
[[UK]Byron Beppo xxxix: The Nursery still lisps out in all they utter – Besides, they always smell of bread and butter].
[UK]D. Jerrold Men of Character I 76: I know him as I know my nails – a nursery thief – a bread-and-butter footpad.
[Aus]Dead Bird (Sydney) 21 June 3/1: Every boarding-school bread-and-butter miss knows that yarn.
[Aus]‘Price Warung’ Tales of the Early Days 131: What the devil Gov’ment meant by sending me bread-and-butter misses who turn sick at a flogging and faint at the use of the tube-gag [...] I don’t know.
[UK]D. Cotsford Society Snapshots 80: But surely, mother,m there’s no demand nowadays for the bread-and-butter miss, except perhaps by widowed and decrepit peers .
[UK]Leeds Mercury 10 Feb. 8/1: She is a most charming creature [...] and not for one moment would I wish her to revert to the manner of the simpering ‘bread-and-butter’ miss.
[Aus]‘Henry Handel Richardson’ Aus. Felix (1971) 31: None o’ your ethereal, die-away, bread-and-butter misses. There’s something of Till there is.

2. plain; thus as n., a plain woman.

[UK]D. Jerrold Men of Character 108: She was not a maudlin girl [...] to give herself red eyes for a bread-and-butter face and curly hair.
[US]Monroe & Northup ‘College Words and Phrases’ in DN II:iii 136: bread-and -butter, adj. phr. ‘A bread-and -butter girl’ is a very ordinary sort of girl, of no brilliancy.
[UK]‘Doss Chiderdoss’ ‘Habits’ Sporting Times 16 Jan. 1/2: She’s no bread-and-butter.
[UK]P.C. Wren Odd – But Even So 15: He wondered how on earth he had ever come to fall in love with Marie Bardsley, a bread-and-butter-Vicarage-Miss if ever there was one.
[UK]J. Braine Room at the Top (1959) 38: She always seems a bit insipid to me [...] strictly the bread-and-butter Miss.

3. basic, fundamental, quotidian.

[UK]Leicester Chron. 19 Oct. 4/1: The assault was a bread and butter affair.
[Aus]Bulletin (Sydney) 20 Oct. 19/2: There is not a critic of note in Berlin who will listen with patience to the sentimental inanities of the bread-and-butter romance familiar on the English stage.
[US]‘A-No. 1’ From Coast to Coast with Jack London 119: [He] carefully took stock of our vehement denunciations of his ‘bread and butter’ line.
[UK]‘Ford Madox Ford’ Man Could Stand Up 38: They had the same sort of good, bread-and-butter brains.
[UK]Morpeth Herald 9 Apr. 8/5: Bread and Butter Question. Can Capitalism Succeed?qua.
[US]Pittsburgh Courier (PA) 17 Feb. 7/1: Katrina Green [...] lost her bread and butter slave [...] because of the publicity.
[US]Lait & Mortimer USA Confidential 165: One reason for the present sorry plight of the movies is that some who manufacture them have contempt for the bread-and-butter customers who make it all possible at the box-office.
[US]L. Bruce Essential Lenny Bruce 131: This guy writes a bread-and-butter column [...] he’s afraid to knock cause they’ll lose the ads.
[UK]P. Fordham Inside the Und. 79: Bread-and-butter crime is [...] extremely dull in nature.
[UK]J. McClure Spike Island (1981) 115: You’re working right from the bread-and-butter stuff [...] right up to the heavy level.
[UK]Guardian Media 21 June 59: The bread and butter revenue [...] is generated by a team of contracted telesales workers.
[UK]N. ‘Razor’ Smith Raiders 1: This lack of ruthlessness [...] was probably the reason why he was still a bread-and-butter robber and had not been invited on to any of the major robbery teams.

SE in slang uses

In phrases

bread and butter fashion (adv.) [the proximity of the bread and butter, which ‘lie on’ each other]

describing sexual intercourse.

[UK]Grose Classical Dict. of the Vulgar Tongue ms. additions n.p.: bread and butter fashion. One slice upon t’other. John and his maid were caught lying bread and butter fashion.
[UK]Grose Classical Dict. of the Vulgar Tongue (2nd, 3rd edn) n.p.:
[UK]Lex. Balatronicum.
[Ire]‘A Real Paddy’ Real Life in Ireland 165: You must lay, said the jolly first luff, bread and butter fashion.
[UK]‘Jon Bee’ A Dict. of the Turf, The Ring, The Chase, etc. 16: When slices are placed face to face the butter is in the middle, and ‘bread and butter fashion’ that couple must lie, who inhabit a bed large enough for one only.
bread and butter letter (n.) (also bread-and-butter note) [note journalistic jargon bread and nutter column, a column fuelled in the main by press agent handouts and similar varieties of free publicity for those who send it to the writer; such a column harms no one, ‘butters up’ a variety of individuals and keeps the writer off the breadline]

a letter of thanks sent to one’s host shortly after having enjoyed their hospitality.

Home Notes (London) 5 175: The ‘bread and butter letter,’ as it is sometimes called, because it is supposed to be an expression of thanks for what bread and butter stands for. should be written within twenty-four hours after arrival at one's destination.
[US]Ladies’ Home Jrnl 1 64: A Bread-and-Butter Letter (as it is called) is due to your hostess, telling her of your safe arrival home, and speaking of your pleasant visit at her house.
[US]W.D. Howells Pair of Patient Lovers 82: His prompt bread-and-butter letter [DA].
Proc. State Farmers’ Instit. (OH) 97: When the girls go away on a visit and come home, they have a fashion of writing what they call a "bread and butter letter" back to the lady who entertained them.
[UK]Daily Press (Newport News, VA) 4 Oct. 5/3: Following a Sunday spent at the house of friends a ‘bread and butter note’ must be written.
[US]S.V. Benét Young People’s Pride 199: I’ll write you a charming bread-and-butter letter of course.
M.K. Rawlings Cross Creek 173: There came to me in the mail a copy of the Boston Cook Book, even ahead of the conventional bread-and-butter letter.
[UK](con. c.1918) D. Holman-Hunt My Grandmothers and I (1987) 6: Such a stupid bread-and-butter letter from Ada Wilkins.
[UK]G. Melly Rum, Bum and Concertina (1978) 107: On returning to Chatham I wrote a fulsome bread-and-butter letter to her.
[US]B. Gutcheon New Girls (1982) 325: The other letter was essentially a bread-and-butter letter from Lisa.
bread-and-butter teeth (n.) [large and white, they resemble slices of bread and butter]

buck teeth.

Hobart Town Mag. (Van Dieman’s Land) 1 241: In the centre, projecting a little over the under lip, were two dentrical organs [...] of that class usually denominated ‘bread-and- butter teeth’.
[US] in DARE.