I SCREAM, YOU SCREAM, WE ALL SCREAM FOR…: “Baptiste,  it’s show time,” Karl Lagerfeld bellowed on the  gigantic set where he was directing a series of minifilms featuring Rachel  Bilson and Baptiste Giabiconi for the  forthcoming U.S. launch of premium ice-cream brand Magnum.
 Some  in the room snickered, as “Showtime” is the title of Giabiconi’s first  single and video as a breakout singer. On this day, the chiseled model  was cast as an ill-tempered young photographer, which he played to the  hilt for Lagerfeld’s cameras, donning dark glasses and hurling  expletives.
 Bilson, upstairs getting her hair curled for the  scene, assured that her character — an ingenue actress/model and the  object of Giabiconi’s lens — doesn’t take the abuse lying down. “I threw  my wig at him, so I get him back,” she said, a knowing smirk curling on  her lips.
 Lagerfeld certainly put Bilson through her paces,  also casting her as an art student and a prima ballerina. “With the  pointe shoes and all, which is very painful,” she noted, marveling at  the Parisian locations, including the famous music hall Folies Bergère,  and Lagerfeld’s multitasking brilliance.
 In the art-school  vignette, Bilson is released from her creative block after indulging in  an ice-cream break, Lagerfeld explained between sips of diet cola and a  protein snack.
 The three 90-second spots are to premiere at the  Tribeca Film Festival on April 21, and then land on Magnum’s Facebook  page, part of a marketing onslaught that will include TV commercials and  a print campaign, also featuring Bilson and lensed by Lagerfeld. The  latter are to break in May.
 Shipments of Magnum, Unilever’s  biggest ice cream brand, are starting this month in the U.S. In Europe,  the brand is known for its silky chocolate-covered ice cream on a stick —  and such celebrity ambassadors as Eva Longoria and  Benicio del Toro.
 “I love to do advertising, on both  sides of the camera,” said Lagerfeld, who was mobbed by youngsters on  the street when he stepped away for a lunch break; most recognized him  from his appearance in a new Volkswagen commercial in Europe.
  Bilson, meanwhile, is soon heading to North Carolina to start filming a  new pilot series called “Hart of Dixie,” reuniting her with “The O.C.”  creator and executive producer Josh Schwartz. In it,  she portrays an Upper East Side doctor transplanted to a small town  peopled with eccentric characters. “It’s kind of like ‘Sweet Home  Alabama’ meets ‘Doc Hollywood,’” Bilson mused, relishing the prospect of  donning city-slicker threads for the role.