Green’s Dictionary of Slang

‘a smiling, doll-like attractive girl’ (Ware); a term of affection, esp. by a father to a daughter; cite 1880 refers to a baby.

1868		W.S. Gilbert [burlesque title] The Merry Zingara; or, The Tipsy Gipsy and the Popsy Wopsy.
1869		Belgravia (London) Oct. 316: Going to the next desk, I read : ‘My darling Popsy-Wopsy, — Dinner seven sharp ; salad all day in cold water; uncle John comes, mind. Georgy.’ No doubt this was a message from Georgy to his Popsy.
1875		‘Aliph Cheem’ Lays of Ind (1905) 57: ‘Think, my precious popsy-wopsy, / Only think what would be said’.
1878		G.W. Hunt [perf. George Leybourne] ‘The Gay Masquerade’ 🎵 With dear ‘popsy wopsy’ so gaily arrayed.
1880		Bulletin (Sydney) 18 Dec. 12/1: A precious popsy wopsy—give its mammy, den, a kiss, / A pretty darling, itsy witsy ting!
1880		Liverpool Mail 5 Sept. 6/5: ‘Nunc,’ said Popsy, still lingering..
1888		E.J. Goodman Too Curious 112: Now go along like a good little popsy-wopsy, and don’t cry to sit up .
1892		Ally Sloper’s Half-Holiday 19 Mar. 90/3: Bless me if the little popsy-wopsy hasn’t been collecting all the old circus hoops and covering them with her old muslin skirts [F&H].
1895		Truth (Sydney) 20 Jan. 3/5: I haven’t any young women bar yourself, you darling little popsey-wopsey.
1901		Marvel XV:388 Apr. 2: How do, my little poppsiwopsi?
1909		J. Ware Passing Eng. of the Victorian Era.
1913		Sport (Adelaide) 31 May 12/4: Should his popsy-wopsy hear of it there will be a scene.
1916		P. Kyne Cappy Ricks 186: ‘And you’ll be all alone, popsy-wops,’ she added.
1925		S. Lewis Arrowsmith 222: There, my popsywopsies, up to bed we go!
1930		W.S. Maugham Bread-Winner Act I: Hullo, popsy-wopsy.