Source : Webster's Revised Unabridged Dictionary (1913)

Toadeater \Toad"eat`er\, n. [Said to be so called in allusion to
   an old alleged practice among mountebanks' boys of eating
   toads (popularly supposed to be poisonous), in order that
   their masters might have an opportunity of pretending to
   effect a cure. The French equivalent expression is un avaleur
   de couleuvres. Cf. {Toady}.]
   A fawning, obsequious parasite; a mean sycophant; a
   flatterer; a toady. --V. Knox.

         You had nearly imposed upon me, but you have lost your
         labor. You're too zealous a toadeater, and betray
         yourself.                                --Dickens.