https://newsone.com/3068179/newsone-now-exclusive-michelle-obama-election-2014/ . The section I am talking about begins at 7:07 of the interview (by the way, it was a radio interview, so it's audio only).
To put it in the context of Henry Louis Gates' theory of "Signifying," note that the interviewer, Roland Martin, is a prominent African-American TV news journalist, that he uses the phrase "souls to the polls," which is clearly what Gates' would identify as a 'Black trope," and that he and Ms. Obama are both chuckling. Her "Fried Chicken" comment is signifying in the sense that it is said with an awareness of a white stereotype of African Americans, and (moving on the perpendicular access of meaning that Gates identifies as being aware of and in contradiction to the white signification, or literal meaning, of fried chicken as an African American stereotype), the statement is ironic, a parody (or pastiche) of white attitudes toward African-Americans.
If you want to push this a little further, read the online comments about this statement. The fact that people took this statement literally, claiming in the blogosphere that she, and by extension, the Democrats, were literally offering fried chicken to African-Americans who voted Democrat, is further proof of Gates' theories. By reacting strongly on the literal level and ignoring the laughter and other context clues that it is a joke, it confirms that many people from the dominant culture clearly don't understand what Africans Americans are saying even when the grasp the meaning of individual words because they are unable (or, in some cases) unwilling to read the cultural context something is saying.