Outkast -- Reunited at Coachella ... While Prince Watches On

The Purple One doesn't make the trek out to Coachella for just any performance ... but when it's rap duo Outkast reuniting after 8 years, Prince makes an exception.

Big Boi and Andre 3000 headlined night one of the annual concert -- performing their biggest hits like "Bombs Over Baghdad" and "So Fresh, So Clean."

Halfway through the gig Andre got all fanboy when he couldn't resist telling the crowd his idol Prince was watching from the side of the stage. It's pretty cool to see him so humbled.