Rihanna is such a professional that even if she feels ill she hits the stage...She's actually such a pro that she will move to the side to throw up and come back and rock the stage.

While performing at Lisbon's Atlantico Arena, Rihanna was giving a pretty energetic performance of What's My Name, and the crowd was really feeling the performance. Then she jumped offstage to throw up.

Sources say the reason she threw up was a mix of exhaustion and stress....which translates to Rihanna has been partying too much. Hey girls just wanna have fun right?

After the incident, Rihanna tweeted: 'yep! I ran off stage to throw up, halfway thru Whats My Name...made it back juuust in time for RudeBoy.'
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