House niggers were slaves who were more acceptable in demeanor and appearance to their owners than the darker, more aggressive field niggers. Docile males, fuckable women, those who could cook or clean, the elderly and disabled, etc.
Any slaves deemed non-threatening or too weak to work the fields were candidates to work inside the house and become house niggers.
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I really wanted to go to that Bukake because I thought for sure that you were going to be on the receiving end. - Ryan Knox to Jeff Steward