Green’s Dictionary of Slang

red rag n.

1. the tongue; thus too much red rag, speaking too long and too loud, give the red rag a holiday, be quiet, stop talking, wag the red rag, to talk to excess [its colour and its ‘flapping’].

[UK]The tongue combatants 3: [A]ll your neighbours [...] wish the Feaver of your Red-rag were cured by the applying of a Razor.
[UK]B.E. Dict. Canting Crew n.p.: Red rag a Tongue. Your Red-rag will never lie still, your Tongue will ne’re be quiet.
[UK]New Canting Dict. [as cit. c.1698].
[UK]B.M. Carew Life and Adventures.
[UK]Kentish Gaz. 13 Feb. 2/3: Show me that glib speaker, / Who her red rag, / In gibe can wag.
[UK]Grose Classical Dict. of the Vulgar Tongue n.p.: Red rag. The tongue. Shut your potatoe trap, and give your red rag a holiday; i.e. shut your mouth, and let your tongue rest. Too much of the red rag (too much tongue).
[UK]G. Andrewes Dict. Sl. and Cant.
[UK]Lex. Balatronicum [as cit. 1785].
[UK]Egan Life in London (1869) 278: If you don’t hold that red rag of yours, I’ll spoil your mouth for a munth.
[UK]Sussex Advertiser 14 Apr. 4/3: This affair, about which so much ‘red rag’ has been lavished away, and so much blunt won and lost.
[UK] ‘The Slap-Up Cracksman’ in Swell!!! or, Slap-Up Chaunter 42: Who would be a lob or stag? / And splitting, wag his d—d red rag.
[UK]New Sprees of London 21: [I]t is also indispensably necessary that you have a plentiful portion of flash patter ready at the tip of your red rag ; .
[Aus]Bell’s Life in Sydney 16 Sept. 3/2: Let lose your red rag. Pelt him with hard words.
[UK]A. Mayhew Paved with Gold 254: He was the knowingest ‘nob’ that ever wagged the ‘red rag’ (tongue).
[UK]E. de la Bédollière Londres et les Anglais 317/2: red rag, la langue.
[US]Letters by an Odd Boy 161: I can understand that [...] my face may be a ‘frontispiece,’ my tongue a ‘red rag,’ and my nose ‘a smeller’.
[UK]W.S. Gilbert Dan’l Druce i: Stop that cursed red rag of yours, will you? [F&H].
[UK]Shields Dly Gaz. 28 May 2/4: Don’t you trouble to wag your red rag at me.
[US]Minneapolis Jrnl (MN) 24 Jan. 19/3: Red rag —the tongue.
[UK]Western Dly Press 24 May 3/6: ‘Red rag’ was, in early days, a slang term for the tongue.

2. a menstrual cloth or sanitary towel.

[UK]Farmer & Henley Sl. and Its Analogues.
[Aus]N. Keesing Lily on the Dustbin 31: ‘I’m on my rags’ (or ‘red rags’) is [...] curiously reverting to a time before sanitary napkins were widely available and when strips of towelling and sheets were worn during menstruation.

In derivatives

red raggism (n.)

unrestrained, critical speech.

[Aus]Franklin & Cusack Pioneers on Parade 60: You’d better not let any one hear you talking like that here [...] it’s looked upon as red-raggism.

In phrases

mount the red rag (v.)

to blush.

[UK]H. Nisbet Bushranger’s Sweetheart 33: Who would take her for twenty-five, and an old traveller, to see her mounting the red rag like a girl of fourteen?