OPENED FEBRUARY 27, CERT 12A, 90 MINS Frequent Ben Stiller collaborator John Hamburg (he co-scripted Meet The Parents and Zoolander) assumes writing/directing duties for his pal's latest, another in the genre of contemporary romantic farce that Stiller has made his own. The wafer-thin plot has Ben starring as deeply cautious risk assessor Reuben Feffer, cuckolded on his honeymoon by new bride Lisa (Will & Grace's Debra Messing) and forced to return to New York, where he enters into a relationship with free-spirited school pal Polly Prince (Jennifer Aniston). And that's about it. Nothing exceptional happens but what does happen is very, very funny. Nobody portrays comic embarrassment better than Stiller, and Hamburg gives him free rein to indulge himself with numerous pratfalls and close encounters of the horrifically unhygienic kind. Aniston once again proves she's a gifted, natural comedienne, old pros Philip Seymour Hoffman and Alec Baldwin lend solid support, and the deeply underrated Hank Azaria almost steals the film as Reuben's priapic French scuba instructor nemesis. Gloriously juvenile fun.