Green’s Dictionary of Slang

1. a beggar who poses with a number of fake illnesses; thus the act of posing as such.

1806		Annual Rev. for 1805 IV 620/2: One should imagine, by the phrase of sham-abram, that originally it must have meant one really lunatic.
1843		Kendal Mercury (Cumbria) 18 Feb. 3/3: He subsequently appeared to be very ill [...] The surgeon, however, declared him to be an imposter, though his sham-abram had been of the the first order.
1881		Preston Chron. (Lancs.) 6 Aug. 4/6: Lo! if her madness and lunacy did not instantly vanish; she had been taking the combined role of sham-Abram and Bess-o’-Bedlam.
1885		R. Burton Arabian Nights I 331: The sham-abraham kept saying to them ‘Open your eyes or you will be beaten afresh’.

2. a fake.

1828		‘Punch & Judy’ in London Lit. Gaz. 9 Feb. 84/2: Punch: There, get up, Judy my dear; I won't hit you any more. None of your sham-Abram.
1858		‘A. Pendragon’ Queen of the South 133: Shall language be expunged because we dread to listen to it? O, ye sham Abrams, where all is more or less delusive, ‘judge not, lest ye be judged’.
1861		R.F. Burton City of the Saints 192: The Abrahams of Great Salt Lake City are mere ‘sham Abrams.’.
1885		Edinburgh Eve. News 7 Oct. 3/5: The thing’s [i.e. an umbrella] a Sham-Abram and simply not in it with mine!