She also sang "'My Songs Know What You Did in the Dark" with Fallout Boy.
Swift, 23, must have gotten close with several of the Angels -- she patted Cara Delevingne's backside on the catwalk and ogled Karlie Kloss' cleavage.
Angel Lily Aldridge Instagrammed a few polaroids of herself hanging out with Swift, Delevingne and Erin Heatherton.
"Besties!!" she captioned the snap.
In turn, Swift tweeted "The best things always happen on the 13th!"
Aaron Carter is still in love with Hilary Duff
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