Karen O, best known for fronting the Yeah Yeah Yeahs, has long been crossing over into other mediums: She scored Spike Jonze’s Where the Wild Things Are and directed music videos for bands like the Liars and Foetus. This weekend she’ll turn into the nightmare-ish, singing/yelping den mother at the heart of Stop the Virgens, a psycho-opera she co-created with KK Barrett that features insane costumes, new music, and high-watt collaborators like the Creator’s Project and director Adam Rapp. (The show opens tonight at St. Ann’s Warehouse and runs through October 22.) We spoke to Karen O about dream worlds, the importance of live shows, and becoming a theater person.