That's “Designated Ugly Fat Friend”—and while our heroine Bianca (Mae Whitman) is neither ugly nor fat, she still serves to make her best friends (Skyler Samuels, Bianca A. Santos) look better. So she reluctantly enlists the neighbor boy she can barely stand (Robbie Amell) to coach her out of her DUFF-hood. Josh A. Cagan's script has some cornball gimmicks and it cuts the sex in Kody Keplinger's novel to preserve a PG-13 rating. But it also (with a big help from Whitman, finally ready for her close-up) softens the edges of Keplinger's snotty, full-of-herself Bianca. As in any romantic comedy, star chemistry is essential, and this movie's got it: Whitman and Amell have an easy rapport that probably makes Cagan's dialogue sound snappier than it is and smooths Ari Sandel's sometimes jittery direction. J.L.