If you're black, how do you answer "Oh you're a professor? So you teach African Studies?" In a comment to How do you answer &quot;Oh, you&#39;re a professor? What do you teach?&quot;, @JohnSmith wrote

I'm black so it generally goes &quot;Oh you're a professor? So you teach African Studies?&quot; I generally storm off.

John's reaction is understandable.  But I'd like to explore some alternatives.  Note that John's experience is not isolated to black professors.  For example, another comment on that thread pointed out that some stupid people tend to assume a female professor teaches gender studies.
How do you answer &quot;Oh you're a professor? So you teach African Studies?&quot;
I'm looking for a lot in an answer.  It should:

be short
open the thoughtless person's eyes
allow for a graceful exit by both parties

Here is an example of the kind of answer I'm looking for:

Question posed by a white person to a transracial black adoptee: &quot;What country were you born in?&quot;
Answer: &quot;Long Island.&quot;

Edit: Please assume there was no hidden agenda.  Just some combination of garden variety cluelessness and stereotyped thinking.
Typical scenarios: neighborhood picnic... parent meeting at your child's school... standing in line at the grocery store....
Edit 9/18: This question closely mirrors the other, in which the questioner is not an academic, and the academic feels socially isolated and uncomfortable, and unsure how to respond.
What's different here is that there is an additional layer of discomfort related to being an obvious member of an under-represented group.  Think of a Venn diagram.  The set of people interested in &quot;So you teach African Studies&quot; question is a subset of those interested in the original &quot;What do you teach?&quot; question.
I would ask enthusiasts of this site who have no personal interest in this question to allow those of us who do, to explore this very real problem -- even if you yourself have never experienced it and do not anticipate experiencing it.
But who knows, you might encounter a similar problem some day on a trip to an overseas conference, or in an unfamiliar corner of your own country.
Permitting an exploration of this question can potentially be useful to white, male, straight, in short, hegemonic, academics in another way.  If your department is one of the many that are striving to diversify, this question is an example of things that matter to the diverse candidates you are trying to recruit.
Edit 9/22: Reading the answers and comments led me to an idea.  (If the question gets re-opened again(!) I can post it as an actual answer.)

Well, no, but if you're trying to choose an African Studies course for next semester, you're welcome to bounce some ideas off me.

(I have a feeling this is the kind of answer I'd get in a lot of trouble with from my children.  They'd say it's too annoying....)
What's wrong with a sensible answer:  "No, I teach Chemistry."