A sweatered, stuttering Jason Lee trying to carry a movie all by his lonesome is not a pretty sight. A Guy Thing is proof that Lee—clearly misguided in taking another schmuck-fiance role after Stealing Harvard—needs a little help: Whether supported by a smartass (Ben Affleck) or a dumbass (Tom Green), Lee is at his best when he has someone with a little personality to play off of. In A Guy Thing, that person is supposed to be a quirkified Julia Stiles, but the only thing interesting about her undercooked character is her flippy hair. The story is based on the post-bachelor-party confusion of Paul (Lee), who wakes up next to tiki girl Becky (Stiles) despite being very much in love with his betrothed, Karen (Selma Blair). The fun starts when Paul keeps running into Becky—he should have known better; they do live in small-town Seattle—and discovers that she’s Karen’s cousin. The lies that follow as Paul tries to figure out what happened revolve around crabs, dirty women’s underwear, and diarrhea, and the so-called spark between Paul and Becky is most fully displayed when she talks him into jumping his car on a hilly road. (“I just never thought I’d do anything like that!” he marvels.) Scripter Greg Glienna (Meet the Parents) didn’t bother developing any of his characters—which leaves the film’s usually competent actors with nothing to grab on to: We know that Karen is wonderful because everyone keeps saying so, that Becky is a free spirit because she keeps changing jobs, and that Paul is in the wrong relationship because he, uh, has to keep lying about the woman he spent the night with, I guess. The at-the-altar moment of truth is mildly amusing, if only for Larry Miller’s part as a Paul-hating minister; the ending is a surprise, if only for of the rest of the movie’s completely haphazard plot development. Unless you’re familiar with Lee’s better work, you’ll probably leave the theater with the same view of the man some preteen girls at my showing expressed after Paul giddily flew his car over the hill a second time: “Dork!” —Tricia Olszewski