What does George say about Candy and Lennie visiting with Crooks in Of Mice and Men?

George is not comfortable with the idea of Candy and
Lennie visiting with Crooks.  Certainly, part of this is the residual attitude that
White society held towards people of color, specifically African- Americans.  This is
not something that is revealed in anything that George says, but rather it is something
that is intimated and something that is evident in the manner in which George looks at
the setting.  The only thing that George openly conveys is his discomfort with the idea
that George and Candy are sharing the dream of the farm with someone else.  George is
seeking to keep things as quiet as possible regarding their dream.  The only reason that
Candy knows is because of his money contributed.  For George, the idea that Lennie and
Candy would be discussing this dream in front of another person is uncomfortable for
George.  It can be inferred that Crooks, being African- American, represents a level of
difference that someone as defensive as George would not be able to fully appropriate. 
After being humiliated by Curley's wife and seeing George's reaction, Crooks himself
withdraws from his participation in the dream, conveying the level of disapproval and
resistance that George displays towards Candy and Lennie visiting with the
stablehand.