I only know Louis Farrakhan said that, and elsewhere I had only heard it used in a mocking way, not seriously, by an anti-Obama commentator.

And I don't recall Barack Obama ever addressing it - but then again, politicians running for office would have to no time to eat, breathe, or sleep if they addressed every single thing someone said about them, good, bad or otherwise.

I do not hold it against Barack Obama for not commenting on it, nor do I hold it against John McCain for not commenting on it, either.