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Rihanna gave the paps some serious attitude when she landed at Los Angeles International Airport on Wednesday night, but even when she's making ugly faces, she's still smokin' hot!

We're not sure what had her in a mood, but if we could guess, we'd say it has something to do with on-again/off-again boyfriend Chris Brown.

Last Friday, after learning that Brown had allegedly hung out with his ex, Karrueche Tran, RiRi tweeted, “Examine what you tolerate, goodbye muthaf*cker ... You give, you get, then you give it the f*ck back." Just 24 hours later Rihanna posted another tweet, writing, “Miss you," along with a snapshot of her cuddling with Brown. And then last night she tweeted, "Never underestimate a man's ability to make you feel guilty for his mistakes." Um, so are they or aren't they back together?