Bring on the shade! Two of music's biggest pop stars might have a "beef" going on...at least that's what Lady Gaga's tweets suggest.

On May 8, Gaga tweeted, "It looks like green hair and mechanical horses are the thing now."

So why is that considered to be a jab at "Dark Horse" singer, Katy Perry?

Well, during her current "Prismatic World Tour," Perry sports a green wig, and at one point during the show, she rides an Egyptian-styled mechanical horse.

Coincidence? We think not!

Gaga's snarky sub-tweet comes as a bit of a shock because of her public vow to remain friendly on the Internet and to not be among the long list of celebrities who fight via Twitter as Billboard.com explained.

Gaga's twitter profile even includes the headline stating that she is, "Spreading love with every intention, forever devoted to the kingdom of monsters."

But maybe Gaga just couldn't take the heat and put "spreading love" on the back burner this time around.

After all, Perry continues to dominate the music charts with hit after hit. Gaga on the hand continues to fade further and further away from the spotlight.

As Pittsburgh Post-Gazette reported, Gaga's latest album "Artpop" was dubbed "Artflop" by critics because of the lack luster sales it generated during its first and second week after its release. 

Not to mention, the album has only managed to sustain one hit "Applause" that still failed to meet the chart topping success as her previous hit singles that include "Bad Romance," "Born this Way" and many others.

Perry also beat Gaga in the war of most twitter followers. Gaga, who used to be number one on the most Twitter followers list, has been outnumbered by Perry who has a whopping total of 52.9 million followers while Gaga has 41.4 million.

Better luck next time Gaga.

Though she's not doing so well on the charts, Gaga's boyfriend Taylor Kinney recently revealed his girlfriend's dedication to hiking while looking her very best.

"We'll hike together," "The Other Woman" actor said during an interview with Glamour magazine. "I'm always giving her flak, like, 'Babe, you can't wear your heels when we're hiking.'" 

Lady Gaga is currently on Tour with her "Art Rave" tour while Perry is on tour right now with her "Prismatic World Tour."

Which one will you be attending?