VIDEO : Katy Perry and Lady Gaga Also Had Twitter Beef With Calvin Harris!

Calvin Harris
is no newbie when it comes to Twitter feuds.
Back in 2011, the Prism singer called Calvin out for pulling out of her U.K. shows last minute. He was scheduled to open for her concerts, but opted against it after getting over the set arrangements.
When asked about rumors he almost worked with Gaga in the past, Harris shared on the BBC Breakfast in 2012 that at the time he was "busy," adding, "You got to pick people whose songs or voice that you like and at that stage, it was before she was very big and they sent me songs that I didn't really like the songs and that's OK. "