The bluntly titled “Zack and Miri Make A Porno” is a cheerfully vulgar love story or a sweet-hearted sex farce, however you want to look at it.

Very much of a piece with Kevin Smith’s previous down-and-dirty, working stiff comedies, the raucous humor here also neatly dovetails with the pants-down funny stuff recently popularized by Judd Apatow. That, and the presence of Seth Rogen doing what he does best, bodes well for this MGM/Weinstein offering, which looks to pocket some nice change in fall release and prove a very popular home viewing title down the line.

If there were any doubt that anyone can make a movie now, “Zack and Miri” dispels it, as the lead characters do it–and the nasty–for the sole purpose of making money. Friends since first grade, Zack (Rogen) and Miri (Elizabeth Banks) have long lived together in a low-end Pittsburgh house but have never been an item, as that would somehow seem weird.

Smith paves the way for the raw stuff to come by opening the floodgates for the sex and potty humor at the outset. There’s scarcely a line of dialogue that doesn’t feature the f-word, a-word, one of the c-or-p words or some variant of them, and it isn’t long until you have to either decide that it’s all intolerably stupid or, more likely, succumb to the downright silliness of it and enjoy the overdose. It would be too much to say that what Smith has come up with here is inspired, but it is pretty funny and very energetic.

An unlikely night-before-Thanksgiving high school reunion sees Zack push for a bathroom quickie with a married former classmate, while Miri embarrasses herself by propositioning the handsomest guy in the room, Bobby Long (Brandon “Superman” Routh), before discovering he’s not only gay but a big porn star, who’s in from L.A. with his b.f. (an amusingly upfront Justin Long).

Inadvertent celebrities when both their asses turn up on You Tube thanks to an opportunistic kid with a videophone, Zack and Miri, their rent overdue and the water and power cut off, have got to find a quick fix for their financial quandary. The title explains their solution, but the big discussion centers on whether or not they can bring themselves to do the deed on camera. Of course they can.

Still, Zack plans the scenario so that Miri won’t be having sex with anyone else in the film, which initially takes shape as a sci-fi takeoff called “Star Whores” (wait, didn’t Mel Brooks long ago do “Spaceballs”?). Zack assembles a motley crew, consisting of “producer” and casting director Delaney (Craig Robinson), his longtime fellow coffee shop workmate who’s comically oversensitive to any perceived insult to his blackness; Lester (Jason Mewes), a young man who can be ready for action at the snap of the fingers; Bubbles (porn legend Traci Lords), who lives up to her name in more ways than one; Barry (Ricky Mabe), a pliable young fellow; Deacon (Jeff Anderson), who qualifies as d.p. by having photographed high school football, and Stacey (“Porn 101” star Katie Morgan), who will do specialty acts.

As lensing gets underway despite an initial setback, Zack can’t believe how much fun filmmaking is, and Miri tells him he actually seems ambitious for the first time in his life. When the time comes for their big scene, for which they never rehearsed at home, it goes differently than either of them would have expected, leading both to assess their relationship in a new way.

What the scene really is, however, is yet another fantasy, now explicit and familiar due to the Apatow stable’s output, of a chubby, geeky guy getting it on with a gorgeous young woman and her digging it. Needless to say, chubby, geeky guys will dig the sight of it. Resolution shows there’s both a closet romantic and a good little Catholic boy still deep inside Smith somewhere.

Chemistry between Rogen and Banks is excellent; he bangs out the crude talk with well-practiced, nonchalant expertise, and she’s totally game, throwing it right back at him. Robinson’s deadpan outrage and acceptance of insanity sees him neatly underplaying everyone else, and everyone else pitches in to create a nutty group portrait of try-anything common folk.

Dead-of-winter Pittsburgh locations create a sense of ever-present adversity that’s funny in itself, pacing is ultra-snappy, production values what they need to be. A post-fade out faux promotional video is worth sticking around for.