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!"
[Elle, E! News]