The Collaborative International Dictionary of English v.0.48:

Sham \Sham\, v. t. [imp. & p. p. Shammed; p. pr. & vb. n.
   Shamming.]
   1. To trick; to cheat; to deceive or delude with false
      pretenses.
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            Fooled and shammed into a conviction. --L'Estrange.
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   2. To obtrude by fraud or imposition. [R.]
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            We must have a care that we do not . . . sham
            fallacies upon the world for current reason.
                                                  --L'Estrange.
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   3. To assume the manner and character of; to imitate; to ape;
      to feign.
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   To sham Abram or To sham Abraham, to feign sickness; to
      malinger. Hence a malingerer is called, in sailors' cant,
      Sham Abram, or Sham Abraham.
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The Collaborative International Dictionary of English v.0.48:

Abraham-man \A"bra*ham-man`\or Abram-man \A"bram-man`\, n.
   [Possibly in allusion to the parable of the beggar Lazarus in
   Luke xvi. --Murray (New Eng. Dict. ).]
   One of a set of vagabonds who formerly roamed through
   England, feigning lunacy for the sake of obtaining alms.
   --Nares.
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   To sham Abraham, to feign sickness. --Goldsmith.
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