This tweet seemed to be in reaction to Swift's comments made to Rolling Stone magazine about a fellow female singer that, though she didn't identify, she claimed had done her wrong. "For years, I was never sure if we were friends or not," Swift, 25, said. "She would come up to me at awards shows and say something and walk away, and I would think, 'Are we friends, or did she just give me the harshest insult of my life?'"
"If somebody is trying to defame my character, you're going to hear about it," Perry, 30, touted to Billboard magazine when asked if her tweet was about the "Shake It Off" singer.
As for her other relationships, the "Roar" singer -- who was married to Russell Brand, reportedly engaged to John Mayer and most recently romantically connected to Diplo -- admits that she doesn't have all the answers. "There is no handbook," she tells the music publication. "In all my relationships, I've learned how I have to be more careful and that it's not up for public consumption."
Whose side are you on? Team Taylor or Team Katy? Stand by your girl in the comments and tweet #ETnow.