Just days after Katy Perry went on Australian TV and joked about Miley Cyrus' tongue, Miley fired back on Twitter and commented about Katy’s ex-man, John Mayer.

You may remember after Katy was asked what it was like to kiss Miley during her Bangerz! Show, she said: "God knows where that tongue has been. We don't know! That tongue is so infamous!"

After hearing what Katy said, Miley Tweeted: "Girl if you’re worried about where tongues have been, good thing your ex boo is your EX BOO cause we ALL know where that tongue has been."