This Katy Perry photo contains
robe, robe de dîner, formel, robe de soirée, formelle, demoiselle d'honneur, and demoiselle d’honneur.
There might also be
robe, balldress, and robe de thé.
Watch Katy's crew prepare the ExtraTerrestrial costumes and dance choreography for her upcoming performance of "E.T." on American Idol THIS THURSDAY, 4/21!