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