Back in 2011, Katy called Calvin out for pulling out of her U.K. shows last minute. He was scheduled to open for her concerts, but dipped out after he got the set arrangements.
Katy was pissed. She tweeted at the time:
He reportedly responded, "Sorry to all who wanted to see me with Katy, her team suddenly moved the goalposts and I was to appear on stage with no production."
FYI ALL UK & IRELAND RELATED SHOWS @CalvinHarris will NOT be joining in on the fun and has CANCELLED last minute.— KATY PERRY (@katyperry) March 28, 2011
Katy was quick to say oh-hell-to-the-no about all that posting back:
@CalvinHarris ...funny the goal post seems to be perfectly fine for New Young Pony Club, Yelle, Robyn, Marina & The Diamonds to name a few.— KATY PERRY (@katyperry) March 28, 2011
Daaaang. The shade is real.
@CalvinHarris or how bout Janell Monae and her 16 piece band... Etc... it's fine, I'm used to you canceling on me, it's become ur staple!— KATY PERRY (@katyperry) March 28, 2011
Katy wasn't the only famous, female singer to rip Calvin a new one on Twitter, either. The next year, he got some Twitter backlash from Lady Gaga prompted by his comments on a U.K. talk show.
When asked about rumors he almost worked with Lady G in the past, Cal shared on the BBC Breakfast 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. They didn't really send me any of the big songs. It's just one of those things."
In response to all that, a ticked off Lady Gaga Tweeted him:
Don't worry, Calvin and Gaga reportedly made up since then. But, we're guessing the Katy fight is still going on, though. We all know she's not a big fan of Calvin's bae T-Swift at all...and apparently not him, either.
never even emailed you @calvinharris I guess it's hard to believe I write + produce my music. cuz I'm a woman I don't know about EDM right?— Lady Gaga (@ladygaga) October 29, 2012