Regarding the "...you know what it do" from my experience that phrase is used within the Black culture as slang to denote familiarity as in "you know what/how I react in this kind of a situation". I really don't think it is that deep.
To date I haven't really posted anything about it but I thought would because of something that just happened a few minutes ago, and aptly demonstrates it's use. I'm watching an episode of "Girlfriends" on TV1 (Their slogan is "Where Black Life Unfolds"). Girlfriends was a long running sitcom about 5 Black women, their friendship and careers and their lives in Calif. Think Sex and the City for Black girls. Anyway, in this eppie, 2 of the main characters, female and male, who are the only attorneys of color at the same law firm and vie for senior partner status. They have also been longtime platonic friends and are co-owners in a joint business. It is Christmas time and they decide to go to a tropical destination for the holidays only to have their flight grounded at a layover/ airport in the Midwest which has to shutdown because of a snowstorm. They seek lodging but because everything is filled they end up in a sh****, unclean motel in the middle of no where, without heat and later power. Hours later William, a tall, big man is so tired he finally decides to sleep on the dirty mattress that has no linen on it. He attempts to coax Joan into bed with him so they can cuddle for warmth but she tells him she can't bear to lie on the mattress because it is so dirty. He in turn lies flat on his back and tells her she can lie on top of him so she won't have to touch the mattress at all. She does and settles in and says "Oh William, thank you, you are so gallant" to which he responds "You know how I do". I have long thought HM meant that she was going to act out or get pissed as she was wont to do in the past when she did not get her way. To what degree I have no idea but clearly one can infer based on her past, it would be more than just a brief pouting period.
ETA: So the word s*h*a*b*b*y must be a banned word?? Why I wonder...what am I missing?