 During dinner , Candie 's staunchly loyal house slave , Stephen ( Samuel L. Jackson ) , becomes suspicious of Schultz and Django 's motives . Deducing that Django and Broomhilda know each other and that the sale of the Mandingo fighter is a ruse , Stephen alerts Candie and admonishes him for his greed . Candie is angered at being fooled and having his time wasted , but contains his anger long enough to theatrically display his knowledge of phrenology , which he uses to theorize why slaves frequently fail to kill their owners , despite ample opportunity . 
