Iggy Azalea -- I'm So Fancy ... I Crashed HARD Off the Stage (VIDEO)

Iggy Azalea took a massive tumble off the stage she was performing on Friday night ... and the video is intense.

Azalea was rapping her hit song "Fancy" during a pre-VMA party at the Avalon when she lost sight of the stage and went down like the Titanic.

It's been rough going for pre-VMA stuff. A dancer was bit Friday by an Anaconda during a Nicki Minaj rehearsal.

As for Iggy ... security helped the 24-year old back onto the stage ... and of course, she played the whole thing off like a champ.