Reese Witherspoon proved that even the most proper southern belle’s have a sassy side when she stepped out for the LA premiere of her latest flick, How Do You Know, in a sizzling Zac Posen spring ’11 number. The strapless bustier style seems to be the starlet’s silhouette of choice as it hugs her petite frame in all the right places. The dress boasted a sheer black chiffon overlay that was embellished with fuchsia feather detailing to create a playful finish. As we told you earlier this week, the vibrant pink shade (that has been dubbed honeysuckle by the Pantone Colour Institute) is the colour of 2011 and it looks like Witherspoon isn’t waiting until the New Year to try this hue on for size. The blonde beauty completed her look with a sleek pair of YSL Tribtoo patent leather pumps and simple drop earrings that let the sultry gown steal the show.