Dom Hemingway” opens with a scene where Jude Law gives an uninterrupted, unflinching monologue about his penis, an idea that came naturally to the film’s writer-director Richard Shepard.

“I can talk about my cock for hours,” Shepard said at the Cinema Society and Links of London screening of his new film in downtown New York on Thursday night. “Once I wrote that scene, I thought, I get this guy. I get his ego, his sense of humor, his weirdness. The rest of it kind of just appeared.”

The poster for the Fox Searchlight release is similarly-crotch focused, with Dom lounging in a chair with a whiskey and his legs open. “We made all his suits very tight, because he’s been in prison for 12 years,” Shepard explained. “So when he sits, things get shown in ways they shouldn’t.”

Jude Law took credit for that character flaw. “I got this idea with the suit, when he left prison, he got it cut in the wrong areas,” said Law, who packed on a few extra pounds to play his reformed criminal by eating tubs of ice cream, hamburgers and pints of Lager. But that decision didn’t sit well with the film’s tailor. “He kept saying, ‘You can’t do this!’” Law recalled. “It went against his own nature of somebody who wanted the suit to look good.”

The screening and after-party, sponsored by Moet & Chandon at Hotel Hugo, felt more like a cast party for “Girls,” with guests Lena Dunham, producer Jenni Konner, J. Crew creative director Jenna Lyons and Ebon Moss (who, like everybody we talked to, wouldn’t divulge any secrets about the upcoming season four). There was a good reason for that. Shepard, who is dating Konner, has directed some of the most memorable episodes of the HBO dramedy, including the eps starring Patrick Wilson from last season and June Squibb from this year.

Shepard shot and edited “Dom” between seasons 2 and 3, and he’ll be directing two more episodes in season 4. He said it was a challenge raising the $7 million budget for his quirky independent film. “I honestly think there may be some Balkan Wars criminals financing the movie,” he joked. “There were so many producers and executive producers. It was impossible to get it together.”

He also added there are three “Girls” allusions in his film. Without giving too much away, one of them involves naked ping-pong. And Law goes nude in a scene set in the countryside, but that apparently had nothing to do with “Girls.” Explained Shepard: “It made logical sense to the character.”