Is "Them’s fighting words" a right and received English expression?

I came across the phrase ‘Them’s fighting words,’ in the beginning part of a Time magazine (July 12) article in its Swampland section under the title “Don’t mess with the stimulus! It had all your creamed spinach and more.” The author, Michael Grunwald, seems to be defending Obama’s stimulus plan of infrastructure. The sentence in question reads as follows:

You know, the poor thing has no one to defend it but me. And me again. And yet again. So, its infrastructure spending was too “rushed,” and sent cash to the "least difficult and imaginative projects," huh? Them’s fighting words!

I interpret "Them's fighting words" to simply mean "They're fighting words." Can them be used as a subject being followed by the singular of "to be" and a transitive verb (fight) that takes the objective noun (words)? I’m puzzled if this is an established American usage of them or just a fashionable saying.

Solution 1:

It's not grammatically correct; it's a common joking play on bad grammar, particularly on Southern U.S. dialects. I don't know exactly when it was coined for popular usage, but the Looney Tunes cartoons of the 1930s through 1950s certainly made good use of it.

EDIT: here we go; from the American Heritage Dictionary for "fighting words":

The ungrammatical use of them's for "those are" emphasizes the folksy tone of this colloquialism, first recorded in Ring Lardner's Gullible's Travels(1917).

The term "fighting words" itself is a well-known and well-used term, even making it into U.S. Constitutional case law; "fighting words", as in words spoken or written for the sole purpose of inciting a person to fight, are not "protected speech" under the First Amendment.

Solution 2:

I would go so far as to say that the writer missed the full idiom by spelling out "fighting": ordinarily you would say Them's fightin' words!

By which you would mean "By saying that, you are inciting me to argue with you (or, if I feel strongly enough, to start throwing punches at you)." Usually it is said largely in jest as an indication that someone has said something controversial, and rarely with any actual intent to start a physical altercation.

Solution 3:

No, Them's fightin' words is not correct English. This is a widely known American expression in the style of a slightly illiterate western American dialect of the past. A more correct (although less colorful) form would be Those are fighting words, meaning the words someone just said are ones naturally leading to a fight with the one spoken to.