If you ever encounter a lost tribe of primitives who have never experienced films, you could save a lot of time by screening Steve Antin’s Burlesque, since it references and rips off every backstage musical in history in the first 10 minutes alone. Christina Aguilera plays Ali, a plucky Iowa waitress (the part she was born to play!), who moves to Hollywood to pursue stardom and somehow finds it at a musty burlesque club run by Cher. Aguilera was a Disney Channel actress before she became a pop star, so she’s more than adept at self-satisfied mugging, juvenile dramatics and push-up bras, which luckily is all the screenplay requires of her. Burlesque is hoary and pointless enough to form an unofficial quadrilogy with Glitter, Honey and Coyote Ugly, but simple-minded and plotless enough to make those films look like Memento by comparison.