I'd never heard it before, but I am now certain that "I Kissed A Girl" by Katy Perry has been stolen from "House of the Rising Sun" by The Animals.
Don't believe me? Listen to the opening chords of this cover of "I Kissed A Girl":
https://www.youtube.com/watch?v=eYOCJn5xvTE
And then listen to the chords of "The House of the Rising Sun" here:
https://www.youtube.com/watch?v=5A-4VGfx5lU
Tell me there is no connection.