Look at these politician(s) and other media figures responding in an idiotic manner to Bill Maher saying "nigger":

http://web.archive.org/web/20170603165926/http://ew.com/tv/2017/06/03/bill-maher-n-word-real-time/

<<Sasse appeared as a guest to promote his new book, The Vanishing American Adult, and noted about how adults dressing up for Halloween is “frowned upon” more in his state. When Maher said, “I’ve got to get to Nebraska more,” Sasse replied, “We’d love to have you work in the fields with us.”

Maher responded, “Work in the fields? Senator, I’m a house n—-r.” While the interview was not posted to HBO’s official YouTube or social media channels, a clip of the controversial comment was captured by online users and went viral thanks to shares from activists like DeRay Mckesson, among others.>>

Definition of "house nigger" from https://en.wiktionary.org/wiki/house_nigger
1. (dated, now offensive) A black slave that worked as a domestic as opposed to manual labor.
2. (derogatory, ethnic slur, idiomatic) A subservient or accultured [read "encultured"] black person; an Uncle Tom or traitor

Definition of "Uncle Tom" from https://en.wiktionary.org/wiki/Uncle_Tom
1. (derogatory) A black man who is very obedient to white authority.

So Bill Maher is doing one or more of the following: (1) expressing a political message that he is a white Uncle Tom (which if he would have said, there would have been no media outcry) who is very obedient to white authority and doing nothing to fight his "white privilege". This could be mocking said concept of privilege. (2) Joking about how what the Senator said sounds like slavery and that he would rather work indoors: "house nigger" being the only term that came to mind. Or (3) criticizing Nebraska for being containing racists or immigrant laborers who work like slaves.

The attached image has a much more offensive usage of "nigger".