Source : Webster's Revised Unabridged Dictionary (1913)

Mulligrubs \Mul"li*grubs\, n. [Cf. Prov. E. mull to squeeze,
   pull about, mulling numb or dull.]
   1. A griping of the intestines; colic. [Slang]

            Whose dog lies sick of the mulligrubs? --Beau. & Fl.

   2. Hence, sullenness; the sulks. [Slang]