After a day* of pondering, I have figured out an explanation for this:
Known Knowns
It is known something is known. In other words, something is known, and you know it.
ex: All 1964 halves are 90% silver. (There are no ifs, ands, or buts, it is a known fact.)
Known Unknowns
It is known that something is unknown. In other words, something is unknown, and you know about that.
ex: a box of halves (You know that there could be a skunk, or 50 90% halves in there, the box has lots of uncertainty in it)
.
Unknown Unknowns
It is unknown that something is unknown. In other words, you don't know something is unknown.
ex: A new CRHer believes all boxes will contain 1000 halves (The new CRHer does not know (is "unknown") about the fact that some boxes may be shorted, or could contain foreign coins. The box is an unknown in terms of what types of coins you will get as well, not just on silver.)
There are also other types that CoinFetcher did not mention, unknown knowns, known uncertainties, uncertain uncertainties, uncertain knowns, and unknown uncertainties.
Unknown Knowns
It is unknown that something is known. In other words, you don't know something is known.
ex: An ignorant teller believes halves are withdrawn from circulation. (The teller does not know that a known fact of halves being in circulation is true.)
Known Uncertainties
It is known something is an uncertainty.
ex: Silver will go up to $50 next year. (There is an uncertainty as to whether that will actually happen.
Uncertain Uncertainties
It is uncertain that something is an uncertainty. In other words, there is doubt as to whether something is an uncertainty.
ex: Garda culls silver. (There is a doubt as to whether that is uncertain, or whether that is just simply false.)
Uncertain Knowns
It is uncertain that something is known. In other words, you are unsure that something is known.
ex: A new CRHer believes that he might be the only CRHer in America. (He is unsure that people know about silver.)
Unknown Uncertainties
It is unknown that something is an uncertainty. In other words, you don't know that something is uncertain.
ex: A CRHer is astonished that another CRH doesn't keep 40% halves. (The CRHer did not know that other CRHers did not keep 40% halves. He was sure, but now he has an uncertainty over whether a random CRH would keep 40% halves.)
*= It really only took me 10 minutes during morning announcements to come up with this explanation.
So, do you like this explanation or not, CoinFetcher?
P.S.- I have finally joined the "Post is so long you have to bookmark it because you can't read it at one time" club.
Just wanting to know if any one has tried this and had good results. 
