Laurie is making a beeline for the wall after being shooed away by the same woman at the punch bowl. She's looking behind her every so often, knowing that she's getting a few eyes staring straight at her back, and she feels very self-conscious.

As she moves, hands grasping her gown's (http://www.simplydresses.com/_img/PRODUCTS/500/PromGirl-496583309.jpg) skirt so that she doesn't accidentally step on it with her red high-heels, which are now somewhat visible at the toes.

But the thing about constantly looking behind you...you aren't exactly looking forward. So it is quite natural that you might bump into someone, unaware.