This word–meaning, basically, a really bad, pervasive cock-up–was invented in 2009 by the writers of the British TV series “The Thick of It.” Then it caught on. As the Financial Times has noted:
Tearing into the UK government’s budget, opposition Labour leader [Ed Miliband] detailed a list of fiscal shambles – an admittedly impressive array of gaffes from the taxes applied to hot pasties to caravans, from donations to charities and churches – before concluding that the end result was, you guessed it, an omnishambles.
The barb was well timed. The charge of omnishambles was quickly extended to pretty much all aspects of a government that had been granted the benefit of the doubt as it stuck with unpopular austerity policies but whose competence was now in question. The neologism even spawned neo-neologisms. A dispute about whether an independent Scotland could be an EU member became Scomnishambles; a row about badger culls became omnivoreshambles. A flip across the Atlantic to a series of gaffes by the Republican presidential contender gave us Romneyshambles.
In late 2012, omnishambles solidified its triumph by being chosen Word of the Year by the Oxford English Dictionary.
It has still not had much traction in the U.S., however. Other than reporting on the OED’s selection, the New York Times has used it only one time, in a December 24, 2012, blog post.
Shambolic, meanwhile, proceeds apace. Reader Peter Hirsch notes: “Two mentions by Jon Meacham on ‘Meet the Press’ this weekend had even the moderator puzzled.”
notoneoffbritishisms.com 
Hard to read this without noting that “shambles” is a synonym for abbatoir. And while this is clever, we already have the born-in-the-military “cluster-f–k” that is so much more satisfying to say, even if you can’t really use it in print or polite company.
Use its spoonerism them!
Oh yeah, that reminds me. Australians seem to be allowed to say “No wuckers” on daytime television etc. It’s obviously an abbreviation of a spoonerism of something ruder…
http://en.wikipedia.org/wiki/The_Shambles
A street in York.
Actually, at one time streets or even areas of towns in many parts of the UK were “shambles” (either officially or unofficially), though most have long since been demolished. Normally they were “temporary” structures around or in eighteenth/nineteenth century market squares that, over time, became all-but permanent.
The word is pedantic, artificial. “Cock-up” is far more expressive
‘No wuckers’ is just a jovial way of saying ‘no worries’ which is a very prevalent Aussie term. Not rude at all.
I don’t think ‘cluster-f*ck’ is quite the same as omnishambles. ‘Cluster’ implies a group of screw-ups, whereas omni- implies all-pervasive, with every possible thing being a complete mess-up. It is not merely that several things have gone wrong at once, but that every single thing has gone wrong at the same time.
No wucking furries.
The derivation is very rude. No worries > No fucking worries > no wucking furries > no wuckers
But perhaps in Oz the derivation has become forgotten, so there’s no implied use of the word “fucking”.
…Just as many brits would call someone a berk without being conscious of the derivation as rhyming slang for cunt.
Here’s the definitive analysis of the differences between SNAFU, FUBAR, fuck-up, shitshow, and clusterfuck.
(Contains strong language throughout. Obviously.)
https://qz.com/work/1225213/the-difference-between-a-snafu-a-shitshow-and-a-clusterfuck/