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The 'Firework' singer can't wait for trick or treat so she's posted a picture of her in her Halloween clobber a little ahead of schedule.
Along with a picture of her wearing a skeleton mask, Katy tweeted: "Be honest with me, do I look tired?"
She later tweeted another picture of herself with friends in fancy dress at what appeared to be a Halloween party, which she described as "the scariest night of [her] life".