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 Taylor Swift’s feud with Katy Perry did start over a guy — and sources tell Page Six it was John Mayer. 
 
 After Swift mentioned a “straight-up enemy” about whom she’s written a new song, “Bad Blood,” in an interview with Rolling Stone, Perry tweeted to call out a mystery mean girl, “Watch out for Regina George in sheep’s clothing.” 
 
 Swift said in the interview, “Oh, we’re just straight-up enemies. And it wasn’t even about a guy! It had to do with business. She basically tried to sabotage an entire arena tour. She tried to hire a bunch of people out from under me . . . I don’t think there would be any personal problem if she weren’t competitive.” 
 
 Taylor and Mayer had a love affair in 2010 before he dumped her. 
 
 She released the song “Dear John” with lyrics, “Don’t you think 19’s too young to be played by/Your dark twisted games.” 
 
 In 2012, Perry started dating Mayer, who said he was “really humiliated” by Swift’s song. Music sources told Page Six, “Perry started making digs at Taylor from then on.” 
 
 While it was reported that several dancers left Swift’s tour for Perry’s last year, Swift appeared to confirm earlier tensions between them, telling Rolling Stone, “For years, I was never sure if we were friends or not. 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?’ ” 
 
 Reps for the two singers, who were seated in different sections at the recent VMAs, didn’t get back to us. ||||| Is Katy Perry the mystery woman Taylor Swift shades in Rolling Stone? 
 
 The "Shake It Off" singer griped about a pop peer in the magazine's Sept. 25 issue, but in typical Swift style, she refused to name names. Perry implied she's the one Swift declined to identify by referencing 2004's Mean Girls. "Watch out for the Regina George in sheep's clothing..." the singer tweeted Tuesday. 
 
 Does that make Swift Cady Heron in this scenario? And is mutual ex John Mayer the Aaron Samuels? Regardless, the 24-year-old "Mean" singer has yet to reply to the 29-year-old "Firework" singer's tweet. 
 
 The ex-country star implied Perry was the inspiration for the song "Bad Blood," which appears on her new album, 1989. "For years, I was never sure if we were friends or not. 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?' Then last year, the other star crossed a line," Swift recalled. "She did something so horrible, I was like, 'Oh, we're just straight-up enemies.' And it wasn't even about a guy!" 
 
 Swift, who counts Lena Dunham and Karlie Kloss as BFFs, continued, "It had to do with business. She basically tried to sabotage an entire arena tour. She tried to hire a bunch of people out from under me." 
 
 For 15 months, Swift toured the globe to promote Red. Perry kicked off her Prismatic World Tour in May 2014, with concerts scheduled in Australia, France and the United States, among other countries. ||||| Something to roar about. Katy Perry is just the latest celebrity to get hacked on social media. A jokester hacked into her Twitter account on Monday, May 30, and sent direct comments to other users — including Taylor Swift. 
 
 "miss u baby @taylorswift13," the user wrote, pretending to be Perry, 31. Many fans of the "California Gurls" singer liked and retweeted the comment, but quickly figured out that it was a hoax. 
 
 Perry and Swift, of course, haven't been on good terms in quite some time. The former pals, who both dated John Mayer, first feuded in 2014 when Perry allegedly hired some of Swift's backup dancers. 
 
 "She basically tried to sabotage an entire arena tour. She tried to hire a bunch of people out from under me," Swift, 26, told Rolling Stone of an unnamed pop star rival in September 2014. (Insiders exclusively revealed to Us Weekly in September 2014 that Swift's hit "Bad Blood" is about Perry.) 
 
 "For years, I was never sure if we were friends or not," she added. "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?' [Then last year] she did something so horrible. I was like, 'Oh, we're just straight-up enemies.' And it wasn't even about a guy!" (In response, Perry referenced the character Regina George from the 2004 comedy Mean Girls.) 
 
 
 
 The prankster didn't just contact Swift on Monday, though. The unidentified person sent out a derogatory message to #DramaAlert website creator DJ Keemstar (real name: Daniel Keem) and tagged the Twitter handle @sw4ylol. It appears that @sw4ylol might be the one behind the hack. 
 
 "haha follow @sw4ylol #hackersgonnahack," the hacker posted on Perry's page on Monday. The @sw4ylol account, which lists its location as Romania, tweeted: "Who TF is Katy Perry." Perry's fake tweets have since been deleted. 
 
 
 
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– Both Taylor Swift and Katy Perry have had difficult breakups with John Mayer, but Swift insists the story behind a vitriolic song on her upcoming 1989 album "wasn't even about a guy! It had to do with business," she says in an interview with Rolling Stone. Technically, "Bad Blood" might not even be about Katy Perry—Swift demurred from naming names when talking about the song—but by piecing together lyrical and situational clues, BuzzFeed claims "it's not hard to figure out who she's talking about." The song, which Swift tells Rolling Stone wasn't meant "to create some gossip-fest," talks about a fellow female performing artist who for years insulted and sabotaged Swift, including by "[trying] to hire a bunch of people out from under me" and "sabotage an entire arena tour," Swift says. BuzzFeed speculates she could be talking about three backup dancers who reportedly ditched Swift for Perry last year—and E! notes that Perry tweeted today, "Watch out for the Regina George in sheep's clothing...," a Mean Girls reference that could be a hint that Perry is indeed the song's subject. "For years, I was never sure if we were friends or not," Swift says in Rolling Stone of her unnamed colleague. "[Then] she did something so horrible. I was like, 'Oh, we're just straight-up enemies.'" As for why she wrote the song, Swift says, "I'm surprisingly non-confrontational—you would not believe how much I hate conflict. So now I have to avoid her. It's awkward." But, she adds, "Sometimes the lines in a song are lines you wish you could text-message somebody in real life. I would just be constantly writing all these zingers—like, 'Burn. That would really get her.'" The album is due out in October.