For "La La," which shoots later this week, the youngest Simpson sibling will let loose her rebellious side, setting forth on a series of adventures, pranks and hi-jinks as she roams her neighborhood.

Like a cross between an updated "Fast Times at Ridgemont High" and "The O.C.," Simpson's world — as imagined by director Joseph Kahn — is pure teen heaven, composed of surfers, mallrats, BMX bikers and punkers who are all hanging out at parties, fast-food eateries, arcades and parking lots.

Harmless fun — such as riding plastic trays like surfboards — is juxtaposed with troublemaking — including knocking down mailboxes, egging cars and toilet-papering houses. These moments will be captured in a handheld style, so it feels more like a documentary than a video. And outside of a pool-party performance, Simpson's vocals will come across more like dialogue, or an internal monologue, according to the treatment.

Simpson's partners in crime — her girlfriends — don't care if they're making a mess during their night out on the town, starting from the moment they throw clothes around to get ready and sneak out windows to get there. They throw an impromptu pool party (where kids try to charge a cover at the door), make out, dance and watch Simpson sing in a spontaneous performance. They all run wild until day breaks, when everyone sneaks back into their houses as if the night never happened.