That Slavoj Žižek is a funny guy, running around making Lacanian jokes about Rumsfeld, but I have to admit he has a good point (emphasis added):
In March 2003, Rumsfeld engaged in a little bit of amateur philosophizing about the relationship between the known and the unknown: “There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don’t know. But there are also unknown unknowns. There are things we don’t know we don’t know.” What he forgot to add was the crucial fourth term: the “unknown knowns,” the things we don’t know that we know—which is precisely, the Freudian unconscious, the “knowledge which doesn’t know itself,” as Lacan used to say.
If Rumsfeld thinks that the main dangers in the confrontation with Iraq were the “unknown unknowns,” that is, the threats from Saddam whose nature we cannot even suspect, then the Abu Ghraib scandal shows that the main dangers lie in the “unknown knowns”—the disavowed beliefs, suppositions and obscene practices we pretend not to know about, even though they form the background of our public values.