Green’s Dictionary of Slang

(Aus./US) a pancake.

1841		F. Allyn Olmsted Incidents of a Whaling Voyage 153: ‘Flippers’ or ‘slapjacks’ for breakfast.
1850		N. Kingsley Diary (1914) 114: We arrived at the bar in time to [...] get supper &c which consisted of flippers and fried pork [DAE].
1882		L.L. Hubbard Guide to Moosehead Lake 26: Flippers or ‘flap-jacks’ are mixed like bread, except that a little more baking powder is used [DARE].
1863		in R.G. Carter Four Brothers in Blue (1978) 18 Jan. 224: Bob and LeRoy are frying ‘flippers’ (flap-jacks).
1900		Bulletin (Sydney) 18 Aug. 14/2: Has ‘Scotty’ ever camped with a kangarooer, and tasted emu-egg ‘flipper,’ or tail-soup, or grilled-pigeon?
1942		Berrey & Van den Bark Amer. Thes. Sl.