The leads of Kevin Smith's blue movie

Zack and Miri Make a Porno

are counterparts of the 1989 film duo Harry and Sally, only less ambitious.

The same might be said of Smith's movie, an intermittently funny, trash-talking sex farce about platonic friends who, while making a skinflick, inadvertently discover their vocation - and their feelings for each other. Confectionarily speaking, it's an obscenity-glazed sour patch with a toothache-sweet caramel center.

Zach (cuddly Seth Rogen) and Miri (bubbly Elizabeth Banks) are Pittsburgh rowdies and roommates on the striving end of retail. He's a barista, she's a mall cashier, and they're delinquent on the utility bills for their forlorn Pittsburgh flat. During a frigid Steeltown winter, they're in hot water - and freezing cold.

At their 10th high school reunion, Miri hopes to hook up with with her sophomore crush, Bobby Long (Brandon Routh). There, she learns that not only does he play for the other team, he's the prince of gay porn. Highly strung as a show poodle, Justin Long portrays Bobby's domestic partner in the film's slyest performance.

Stone-cold broke, not to mention stone cold, Zach and Miri think that porn may be the answer to their money woes. They enlist Zack's colleague, Delaney (Craig Robinson, very deadpan and very funny) to "produce" the effort.

Smith is a genuinely funny writer - Judd Apatow gives him props for "laying the tracks" that have made possible those Apatow freight trains

The 40-Year-Old Virgin


Knocked Up

. If you can stomach the pot-and-potty humor (I couldn't), there are laughs to be had.

By the halfway mark, Rogen's performance, like his voice, is less cuddly than grating, and the carbonated giggle that is Elizabeth Banks grows flat.

This one's for the Smith cultists.

Zack and Miri Make a Porno ** (out of four stars)

Written and directed by Kevin Smith. With Seth Rogen, Elizabeth Banks, Craig Robinson, Brandon Routh and Justin Long. Distributed by MGM.

Running time:

1 hour, 41 mins.

Parent's guide:

R (extreme profanity, extreme sexual candor, pot and potty humor)

Playing at:

area theaters

Contact movie critic Carrie Rickey at 215-854-5402 or crickey@phillynews.com. Read her blog, Flickgrrl, at http://www.philly.com/philly/blogs/flickgrrl/