Chris Brown's ex-girlfriend Rihanna and his current flame Karrueche Tran are having a virtual mud slinging contest via Twitter, and it seems like RiRi was the one who started it all!

On March 3 the 24-year-old R&B starlet tweeted a photo of a bag of rice cakes with gold earrings and black shades, along with the caption, "Ima make u my b*tch," which many have interpreted to be a racist jab at Tran, who is half-Vietnamese.

After that, Tran referenced the Brad Pitt/Angelina Jolie/Jennifer Aniston love triangle on her Facebook page, writing, "I'm Angelin[a], you're Jen. C'mon you see where Brad is at." Pitt may have been married to Aniston for several years, but as we all know, he's been with Jolie since 2005 and it doesn't look like they're splitting up anytime soon.

Of course, Rihanna still hasn't had enough, as she quoted the lyrics from Lil Kim/Mob Deep's remix "Quiet Storm" yesterday, tweeting, "I'm a leader, yall on some followin s***…comin in dis game on some modeling s***!" Tran is an aspiring model, so it definitely seems like these girls are just getting started...