Jennifer Aniston puts her rabbity pout to good use in this endearingly nasty comedy about a bored cashier in small-town Texas who’s tied down by her husband (John C. Reilly), a sweet-natured doper and couch potato. Her cute but troubled new coworker (Jake Gyllenhaal of Donnie Darko), who equates himself with Holden Caulfield, draws her into an affair, which then opens her up to blackmail by her husband’s peculiarly intimate sidekick (Tim Blake Nelson). The film’s publicists posited Aniston’s character as a sort of Wal-Mart Emma Bovary; in a twangy voice-over she pines, “I wish there was a story about me. Nobody would read it though.” Written by Mike White and directed by Miguel Arteta, who collaborated earlier on Chuck & Buck, this is hardly Flaubert, but it is a fairly beguiling look at moral calculation. 93 min.