The 29-year-old 'Teenage Dream' singer took to Twitter to share a cryptic message shortly after Swift's interview with Rolling Stone about 'enemy' was published, reported Ace Showbiz.
Perry warned her 56.7 million followers of an anonymous mean girl using the ultimate reference from the Lindsay Lohan-starrer 'Mean Girls'.
"Watch out for the Regina George in sheep's clothing," Perry posted.
The posting appeared to be in response to Swift's recent interview with Rolling Stone.
Swift said that her new diss track 'Bad Blood' was inspired by an anonymous celebrity "enemy".
