I've got a 7 y/o (last Wednesday) great niece, (she and her sister are our legal wards) who has exactly the same attitude. Even though she was Cinderella for Halloween, she carried a Spidey goody container, rather than the more traditional Jack O Lantern as her sister (clown) did.
When I asked about the cosutmes she said, "I'm a dead bride". Her sister said I'm a bride, and their younger brother said, "I'm a tiger."
As they were walking away I heard one girl ask the other, "You're a dead bride?".