In the words of Donald Rumsfeld, something that we don't know that we don't know. C'mon Donald.
Each year, we uncover a few more of these unknown unknowns.
A boyfriend or girlfriend in which no one has ever met. The supposed occurance of snuffaluffagi has been dramaticaly increasing due to the popularity of long distance internet dating.
Bob: "Man I hardly ever see Dan anymore since he started seeing that new girl and no one has ever met her. I think he is datig a snuffaluffagus"
Something that one knows they don't know.
There are known unknowns, that is to say that there are things that we know we don't know. (whiskey tango foxtrot, Donald?)
Something that one knows they know
There are known knowns, that is to say that there are things we know that we know.
The dull featureless area between ones anus and his testicles. The only purpose of which is to keep oneself from shitting on ones balls.
I laughed so hard I got ass butter on my gooch.