Keeping Up With The Steins proves that you don't have to be Jewish to make a funny Jewish film. Case in point is the father-son team of Garry and Scott Marshall, with the younger one directing the movie and the older one just about stealing the show as a hippie Jewish grandfather, who teaches his yuppie descendants that there's more to a bar mitzvah than throwing the most lavish party in upscale Los Angeles. The film opens with an aerial shot of a Queen Mary-sized cruise ship, whose bow displays a giant banner "Mazal Tov, Zachary." The theme of the celebration is the last voyage of the Titanic, complete with a huge iceberg mockup, from which emerge a bevy of scantily clad mermaids - and that's just for the appetizer. Hosting the simcha is Arnie Stein (Larry Miller), "agent for the stars," and his trophy wife, whom he met at a Texas wet T-shirt contest. Among the guests, and gnashing his teeth, is Adam Fiedler (Jeremy Piven, also slick agent Ari Gold in the HBO series "Entourage"), Stein's business competitor, accompanied by his wife Joanne (Jami Gertz) and nerdy-looking son Benjamin (Daryl Sabara), whose own bar mitzvah is coming up in a few months. Driving home from the Titanic bash, Adam Fiedler starts obsessing about his heir's bar mitzvah party. It's not enough to keep up with the Steins, he has to put on a bash that will crush and humiliate his rival. Safaris are so 1990 but renting baseball's Dodger Stadium is a possibility. At night, Adam dreams about a line of kipah-wearing Los Angeles Laker Girls as a bar mitzvah highlight. As Adam's fevered mind nears the breaking point, up pops his father Irwin (Garry Marshall), pony-tailed and hippie-clad, along with his spaced-out blonde girlfriend Sandy (Daryl Hannah), whom he met on an Indian reservation where her name is Sacred Flower. Irwin deserted his wife Rose (Doris Roberts) and young family 26 years ago and Adam, who hasn't seen or talked to his father since, has never forgiven him. Father-son relations go from bad to worse when Irwin and Sandy go skinny-dipping in the family pool (in public view but backsides only), though the old hippie has better luck bonding with his grandson Benjamin. Garry Marshall, born 72 years ago under the good Italian family name of Marsciarelli, said that his son, the director, picked him for the grandfather role as "his 10th choice." In truth, agreed Scott Marshall, 37, he had first tried to cast Carl Reiner and Mel Brooks, but both balked at the skinny-dipping part. When he approached his father, the latter asked who would be his pool partner. Told it would be Hannah, Garry quickly agreed. During a joint interview at the Marshall family-built and -run Falcon Theatre in Burbank, father and son noted their qualifications as honorary Jews. Garry, whose credits as comedy writer, producer, actor and director stretch from The Dick Van Dyke Show of the 1960s, through TV's Mork and Mindy, to such films as Pretty Woman and the recent The Princess Diaries 2, pointed to his Bronx boyhood and accent. However, his real education came as a decades-long comedy writer, when he was thoroughly indoctrinated with Jewish and Yiddish humor by his fellow scribes. Scott, directing his first full-length feature film, passed the ethnic test when he had to convince "Steins" producer A.D. Oppenheim that he could do justice to the script by Mark Zakarin, even if he wasn't Jewish. "I told the producer that I married a Jewish woman and therefore, in a way, I have a Jewish mother," said Scott. "Luckily, that was close enough." He further strengthened his case during the interview by referring to "bubbe's latkes" and his education at the private Oakwood School in North Hollywood. "When I was in seventh grade, I went to over-the-top bar mitzvahs all the time," Scott recalled. "At that age, it was about the only place you could meet girls and socialize." He met his future wife at the school and even tried his hand at writing a youthful bar mitzvah party script. After shooting three separate bar mitzvah ceremonies or parties for the movie, Scott Marshall said, "Through this experience, I feel I have finally become a man." Keeping Up With The Steins will open in Israel in the weeks following its May 12 premiere in the US.