She stripped when I went (YOWZA!) but from what I read, it's not at every show.... At Marissa's discretion I gather, based on how "into" that particular performance she is.
I saw Marisa on Conan O'Brian and she said the dance is different every night - she choreographs it herself and will do stripping, as Rob said, at her own discretion. She did not strip the night I saw the show.