RIHANNA flipped out onstage during the London show on her 777 Tour, because her live band wasn't syncing with the backing track.  She stopped the song and said, quote, "What the f*** is that?  Why is the track off from the band?  This is the bull**** we deal with when we're just doing a random, rock 'n' roll tour, all right." Talk about being a diva!

Check out the vid below!

*EXPLICIT*