Cack-handed: Clumsy, awkward, inept. (Chiefly British.) Also cackhanded.
In its endorsement of Barack Obama, the British magazine The Economist included this sentence:
Abroad, even though troops are dying in two countries, the cack-handed way in which George Bush has prosecuted his war on terror has left America less feared by its enemies and less admired by its friends than it once was.
American and British dictionaries differ sharply on the etymology of this term, which is rarely seen on this side of the Atlantic but is common in the United Kingdom. According to Merriam-Webster and American Heritage, the cack in cack-handed comes from English dialect keck, meaning awkward, which in turn came from Old Norse keikr, meaning "bent backward." But here's Michael Quinlon at World Wide Words:
I disagree, as do most British works of reference. The direct association is with cack, another fine Old English term, for excrement or dung. Cachus was Old English for a privy, and both words come from Latin cacare, to defecate.
It almost certainly comes from the very ancient tradition, which has developed among peoples who were mainly right-handed, that one reserved the left hand for cleaning oneself after defecating and used the right hand for all other purposes. At various times this has been known in most cultures. Some consider it rude even to be given something using the left hand. So to be left-handed was to use the cack hand or be cack-handed.
There are similar terms in other languages, such as the French main de merde for somebody awkward or butter-fingered.
Its origins may be vulgar, but cack-handed is regarded only as "informal" in British speech and writing, perhaps no more eyebrow-raising than cacophonous, a word with a related etymology. Still, it's hard to imagine an American equivalent of The Economist—say, the Wall Street Journal—using an American idiom with a related derivation.
(Hat tip for the Economist reference: Glen Turpin.)