In the comments to my post on napoo, xiaolongnu mentioned the expression chin-chin, which I would have placed in the same WWI era and soldierly milieu (major raising glass of claret: “Chin-chin, old chap! Drink up, the Boche await!”); it turns out it goes back much farther than that. The Hobson-Jobson entry begins:
CHIN-CHIN. In the “pigeon English” of Chinese ports this signifies ‘salutation, compliments,’ or ‘to salute,’ and is much used by Englishmen as slang in such senses. It is a corruption of the Chinese phrase ts’ingts’ing, Pekingese ch’ing-ch’ing, a term of salutation answering to ‘thank-you,’ ‘adieu.’ In the same vulgar dialect chin-chin joss means religious worship of any kind (see JOSS). It is curious that the phrase occurs in a quaint story told to William of Rubruck by a Chinese priest whom he met at the Court of the Great Kaan (see below). And it is equally remarkable to find the same story related with singular closeness of correspondence out of “the Chinese books of Geography” by Francesco Carletti, 350 years later (in 1600).
The William of Rubruck citation takes the expression back to the thirteenth century:
1253.— “One day there sate by me a certain priest of Cathay, dressed in a red cloth of exquisite colour, and when I asked him whence they got such a dye, he told me how in the eastern parts of Cathay there were lofty cliffs on which dwelt certain creatures in all things partaking of human form, except that their knees did not bend. . . . The huntsmen go thither, taking very strong beer with them, and make holes in the rocks which they fill with this beer. . . . Then they hide themselves and these creatures come out of their holes and taste the liquor, and call out ‘Chin Chin.'”—Itinerarium, in Rec. de Voyages, &c., iv. 328.
The first evidence the OED finds for English is cited from Hobson-Jobson (I believe that’s what “Y.” means):
1795 M. SYMES Embassy to Ava 295 (Y.) We soon fixed them in their seats, both parties.. repeating Chin Chin, Chin Chin, the Chinese term of salutation.
And these illustrate characteristic twentieth-century use:
1929 J. B. PRIESTLEY Good Compan. II. vii. 439 Chin-chin, Effie my dear, and all the best for Xmas!
1938 HEMINGWAY Fifth Column (1939) I. ii, Downa hatch. Cherio. Chin chin.
1962 ‘M. INNES’ Connoisseur’s Case iii. 34 Going on your way, are you? Well, chin-chin!
1967 P. JONES Fifth Defector iv. 36 Two glasses appeared, with ice tinkling in the Scotch. Paul raised his, smiling. ‘Chin chin.’
For etymology, the OED says only “Chinese ts’ing ts’ing“; this is annoyingly vague both as to “dialect” and meaning—they should really add characters to at least the online edition. Does anyone have more detailed information about the Chinese use of this phrase?