Britney Spears fans are a force to be reckoned with.
Katy Perry learned this the hard way on Sunday, when she seemingly poked fun at Spears' infamous head-shaving incident in 2007. ET spoke with the 32-year-old singer on the GRAMMYs red carpet ahead of her performance, when Perry talked about her new blonde 'do and appeared to throw a little shade at Spears in the process.
"I was just telling you that it's like, the last color in the spectrum that I can do," Perry told ET's Nancy O'Dell and Kevin Frazier. "I've done all of them and the only thing left to do is shave my head, which I'm really saving for a public breakdown. I'm down for that."
WATCH: Katy Perry Gets Political at the GRAMMYs While Performing New Single 'Chained to the Rhythm'
The "Chained to the Rhythm" singer also made a similar joke when talking to Ryan Seacrest on the red carpet about taking a break from music, prior to the release of her catchy new single.
"It's called taking care of your mental health," she explained, adding, "I haven't shaved my head yet."
Not surprisingly, Spears fans weren't happy with Perry on social media. The hashtag #KatyPerryIsOverParty later started trending on Twitter, with a few brutal takedowns.
Some fans even started bringing Perry's reported nemesis, Taylor Swift, into the mix.
WATCH: Katy Perry Tweets Support for Lady Gaga's Halftime Show Super Bowl Performance
Although, Perry has expressed her admiration for 35-year-old Spears before. In August 2014, she paid homage to the "Baby One More Time" singer's infamous matching denim look with her then-boyfriend, Justin Timberlake, at the MTV Video Music Awards 13 years later. Perry was accompanied by rapper Riff Raff, who played the Justin to her Britney.
Watch our interview with Perry at this year's GRAMMYs below: