Can you give us an example of an 'unknown known'?
Whose us?
Certainly, Any behaviour or attitude which can be observed, recorded and that we refuse to acknowledge and are in denial of. E.g. when someone on this forum is outed for having homophobic behaviour but does not acknowledge said behaviour. Since the unknown unknown schtick was invented by Donald Rumsfeld the terms known knowns, and known unknowns and unknown knowns emerged.
Now the thing is about the above is that if you say that these have existed before Donald Rumsfeld then that in itself would be an example of an unknown known.
Philosopher Slavoj Žižek says of the unknown known, It is that which one intentionally refuses to acknowledge that one knows: "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.''
There is also the concept of tacit knowledge, knowledge which we may act on, but not be aware of or able to articulate.
Can you give an example of an unknown unknown?