Katy Perry 'Part Of Me' Music Video: Singer Joins The Marines, Heads To War (VIDEO)

Katy Perry dumps her cheating boyfriend, cuts off her hair, binds her chest and signs up for the Marines in the new video for her latest single "Part Of Me."

The track is a perfect breakup anthem, with lyrics like, "You chewed me up and spit me out / Like I was poison in your mouth / You took my light, you drained me down / That was then and this is now."

Perry premiered the new single at the Grammys, and shortly after, people began to speculate that she wrote the song about her ex-husband, Russell Brand.

However, Perry has denied the song is about Brand, stating she wrote the record more than two years ago. This means that the track could very well be about her other famous ex, Gym Class Heroes frontman Travie McCoy.

She told MTV News recently: "Some people that I work with were like, 'You should just say you wrote it a couple of weeks ago.' I'm like, 'I'm not a d***, I'm going to tell the truth.'"

And added: "I wrote it two years ago when I was writing and recording Teenage Dream, [but] it didn't feel right on the record. I'd have to take out one of my other songs that [made the album] a nice, complete package."

Perry also told MTV that she was "sore and exhausted" after filming the video, in which she goes through a brutal Marines boot camp.

"Thank u to everyone for the love & support on the video, I have SO MUCH respect for anyone serving any role in the service after this shoot!" the singer tweeted on Wednesday.

The song, from the expanded edition of Perry's "Teenage Dream," debuted at the Billboard Hot 100's top spot in February, after she premiered the track at the Grammys.