SAVED BY THE BELLE: In this corner, Hilary Swank, fresh from her acclaimed role as a boxer in “Million Dollar Baby.” In that corner, an obnoxious jerk . . . so let’s get ready to rummmmmmble! Hilary, who’d finished a workout, was exiting the trendy Crunch gym in Hollywood when she noticed a guy pestering a pretty girl for her phone number. The girl rebuffed the creep, who suddenly got verbally abusive — then grabbed her by the arm! That’s when Hilary jumped in and ordered him to back away from the frightened girl. “Yeah and what are you gonna do about it?” the guy retorted. Snarled Hilary: “I’m warning you, BACK OFF!” At the elevator to the parking lot, Loser Boy tried to enter with the two women, but Hilary — who gained 19 pounds of muscle during her intensive “Million Dollar” training — fiercely pushed him away from the doors, which closed before he could recover. Hilary even walked the girl to her car to make sure she got away safely.