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Some of Katy Perry's biggest fans got the surprise of their life last night, when the superstar herself showed up at a special advance screening of her documentary-concert film Katy Perry: Part of Me.

As expected, mayhem ensued at the lucky Los Angeles theater.

Video: 'Part of Me' Details 'Bumpy' Marriage, Says Katy

"When people go and see my movie, I want them to truly know the journey and experience that I went through to get to the place where I'm at now, and hopefully that will inspire them," she says.

Check out the video to witness the sweet surprise.

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Katy Perry: Part of Me, in 3D, hits theaters July 5.