This was sent to my friend James from Australia. It appeared in a local newspaper.
From deep in the bowels of the Australian Taxation Office, new staff instructions regarding emails:-
Quote: "Some emails can be classified as unclassified, and in the process of classifying an email as unclassified, the unclassified email has been classified. But an email that has yet to be classified is not technically unclassified, or classified."
PS - "Clear as mud," means that something is not understandable.