Green’s Dictionary of Slang

champagne.

1840		Thackeray Paris Sketch Book I 34: ‘Ma’am,’ says I, ‘will you take a glass of Sham—just one?’.
1849		Thackeray Pendennis I 33: A bottle of sherry, a bottle of sham, a bottle of port and a shass caffy, it ain’t so bad, hay, Pen?
1870		D. Kirwan Palace & Hovel 478: This is the famous ‘Kate Hamilton’ [...] and her first question is, ‘Will you stand some “Sham”?’.
1873		Sl. Dict. 284: Sham contraction of champagne. In general use among the lower class of sporting men. Sometimes extended to shammy.
1880		Arthur Lloyd [perf. ‘The Costermonger’s Song’ 🎵 I sees the swells their shammy and their nobby things prepare.
1895		C. Crowe Aus. Sl. Dict. 72: Sham, a contraction of champagne.
1903		S.F. Call 22 Nov. 8/2: I’d rather have my harry kick me reg’lar than drink a bottle o’ sham with you.
1905		H.G. Wells Kipps (1952) 109: It was Pearce who said, ‘Kipps, you ought to stand Sham!’ And it was Carshot who found the more poetical word ‘Champagne’.