In the first shot, Lily is seen walking round the corner of the lockers and past the group of bullies. You can also clearly see the boys smirking as the teary eyed Lily walks by.
Lily drops her bag on the floor, and slowly props her locker open, almost knowing someone has done something. In the background you can faintly hear the boys begining to chuckle as she does so.
As the locker door opens lots of litter crashes out, and as they hit the floor the boys can be heard bursting out with laughter. Lily pull a very depressed and diappointed face and sighs at the sight of her locker.