What is "to sham abram"

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.

   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.
   --L'Estrange.

3. To assume the manner and character of; to imitate; to ape; to feign.

   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.