A few days ago I got a card from my friend Steven Levine with a clipping on it from a TLA Video catalog (offering videos of gay interest, including gay porn videos):
We love it when really good porns are made into even better sequels!
Steven asked: "porns"?
Yes, porn used as a count noun, meaning 'porn film'. An instance of a specific type of mass-to-count (M>C) conversion, also seen in spam and e-mail, and in a couple of other examples recently discussed on the American Dialect Society mailing list.
Some very brief background. As I explained in a long geeky posting two years ago, English nouns fall into two classes, C and M, according to their morphological and syntactic properties: C nouns like SHRUB have plural forms, can occur with the article a(n), etc., while M nouns like SHRUBBERY lack plural forms, do not occur with a(n), etc. C nouns typically denote "things" (which can be counted, hence the customary label count noun), while M nouns typically denote "stuff" (often an indivisible substance, hence the customary label mass noun); but the association between C/M classification and semantics is very imperfect. Most nouns belong to one class or the other, but some have both C and M uses, and there are ways of converting nouns from one class to the other, with an associated shift in the semantics.
Many M nouns (like RICE) can be used to denote collectivities of things, and for these there are ways of "individuating" them by combining them syntactically with a C noun — notably in a partitive construction (grain of rice) or in a noun-noun compound (rice grain).
E-MAIL and (computer) SPAM started life as M nouns, inheriting their M classification from MAIL and the food name SPAM. At this stage they could be individuated syntactically: piece of e-mail/spam, e-mail/spam message. Presumably, many people found such usages wordy and awkward, and so converted the M nouns directly to C nouns, so that we now have both a lot of e-mail/spam and a lot of e-mails/spams; many people have both uses, often together. I'll call this M>C conversion, with the associated individuating semantics, countification.
On to ADS-L. On 7 August, Jon Lighter reported on the countification of SLANG, to mean 'piece of slang, slang expression'. He noted that it was not in dictionaries but appeared often in freshman themes, and he unearthed a quote:
"Zig-zag" is a French slang for "drunk." [Edwin James Tippett, Jr., Who Won the War? (Toledo OH: Toledo Type-Setting and Publishing, 1920), p. 147]
Mark Mandel then googled up a bunch of recent examples, among them:
English as easy as pie: Slangs and colloquial expresions. You have to learn the expressions, collocations, slangs and principally know how and when to use them. It's obvious that If you're during a job interview, … (link)
Gay Lesbian and Bisexual question: What are some gay slangs? (link)
And Grant Barrett added:
In Singapore, India, and other English-speaking parts of Asia "slang" is a count noun, not simply a mass noun. I come across such uses by the bucket-loads, even in edited, professional newspapers.
The discussion prompted Charlie Doyle to add another countification:
This reminds me of a usage that I struggle against continually and frantically and (it seems) hopelessly–as does a folklorist colleague: Our undergraduates insist on using the word "folklore" as a count-noun: "Is this saying [song, joke, legend, etc.] a folklore?"
And that brings me around to countified PORN. After getting the card from Steven Levine, I found plenty of examples, among them:
Top 7 horror porns (link)
Probably the best reason to be in a porn is for the money. While, you won't make a ton off of porn itself, it does open doors for other "personal service" … (link)
MAKING a porn is exciting. $2000 cash isn't half bad either (link)
Then I found countified PORNO 'porn film, porn magazine', as in the Kevin Smith movie Zack and Miri Make a Porno and this striking headline:
Pornos rot slower than other magazines (link)
But that turned out to be old news; Ben Zimmer reported that the OED now has cites for PORNO 'a pornographic film' from 1971 (but nothing for PORN as a count noun, except in the rare sense 'pornographer').
No doubt still more examples of countification will turn up. The instinct for brevity is strong.