The only time I find Britney Spears completely intolerable is when she starts to sing—the soft-core number that practically opens this picture, which has her bouncing around in her underwear, being an exception. And this being a movie coproduced by MTV, Spears or someone else is singing full throttle every time a car begins to move or someone enters a club. It’s supposed to be a teen movie about three pals (blue-collar Spears, “trailer trash” Taryn Manning, and upscale Zoe Saldana) who take off from Georgia for Hollywood with a mysterious musician (Anson Mount) who has a car, yet despite the road markers, practically all of it could have been shot inside a couple of square miles. The characters are only slightly less boilerplate than the settings. Dan Aykroyd plays Spears’s dad and Kim Cattrall her estranged mom; a few awful sequences are devoted to a “poem” that Spears’s character writes and Mount’s sets to music, yielding the hit single “I’m Not a Girl, Not Yet a Woman.” Tamra Davis directed the formulaic Shonda Rhimes script, and when the cast is shown during the final credits repeatedly cracking up in blown takes, one would like to think they were laughing at some of the lines they were expected to deliver. 94 min.