MTO EXCLUSIVE: Rihanna Gets WHITE BOY Drunk In The Club . . . Starts FIGHTING Dudes . . . And THROWING UP!! (Pics Of Her Acting Up)

: Pop singer Rihanna is really a MESS. just learned that over the weekend, she got PIZZY DRUNK at the Las Vegas hot spot 1Oak. According to a NUMBER of people there . . . Rih started POPPING OFF to one dude that was there . . . and had to be RESTRAINED by her security.

In addition, a few partygoers claim that Rih went to the bathroom – where she THREW UP at least twice.

This chick is outta control!!!