Green’s Dictionary of Slang

1. (US black) the southern states [puns on SE tan, to beat, i.e. the violence meted out to the black population].

1889–90

Barrère & Leland Dict. of Sl., Jargon and Cant.

2. (US short order) a cup of coffee.

1889

Boston Globe 24 Feb. 18: Five and one and a black-and-tan [...] A plate of doughnuts and a cup of coffee.

3. (US) a person of mixed race.

1891		M.E. Ryan A Pagan of the Alleghanies 26: ‘Well, this ain’t no duck quackin’, Miser Hubbard,’ said the black-and-tan.
1900		Bulletin (Sydney) 10 Feb. 14/3: It has a mixed population of whites, blacks, yellows, and black-and-tans.

4. a drink composed of porter or stout and ale.

1889–90		Barrère & Leland Dict. of Sl., Jargon and Cant.
1900		Bulletin (Sydney) 23 June Red Page/4: Come and have a Man Talk, / A rousing black-and-tan talk! / There are plenty there to teach you, and a lot for you to do. / Your head must stop its whirling / Before you go a-girling. / Come and talk the Man Talk that’s the cure for you.
1902		Dundee Courier 14 June 7/2: ‘Black and tan’ means the slang for stout and bitter.
1958		A. Sillitoe Sat. Night and Sun. Morning 82: Gin-and-orange? I’ll have a black-and-tan.
1966		P. Boyle At Night All Cats Are Grey 71: A black and tan for my old friend, Krueger [...] You can top it up with porter, Mr. Donoghue, the beer’s in it already.

5. a mixture of dark- and light-coloured black people.

1930		Cab Calloway ‘Harlem Hospitality’ 🎵 It’s a taste of life to shim-sham-shimmy with the ‘Black and Tan’.
1935		M. Fulcher ‘Believe Me’ in Afro-American (Baltimore, MD) 20 Apr. 5/1: Black and tan means white and colored patrons.
1944		Cab Calloway New Hepsters Dict. in Calloway (1976) 253: black and tan (n.): dark and light colored folks. Not colored and white folks as erroneously assumed.
1944		‘Jiver’s Bible’ in D. Burley Orig. Hbk of Harlem Jive.

6. (drugs) usu. in pl., capsules of the amphetamine Durophet.

1969		R.R. Lingeman Drugs from A to Z (1970).
1980		S. McConville ‘Prison Language’ in Michaels & Ricks (1980) 526: Amphetamine-barbiturate mixtures seem to have spawned a particularly vivid range of nicknames and images, often arising from the appearance or color of capsules in which they are taken. These include black and tans [etc.].