Welcome to the latest service from Flickr, Flickr Explore, where 500 of the best pictures uploaded to Flickr each day are rotated through a rainbow spewing from the mouth of a Panda.
And no, I'm not making that last part up, and yes, the screenshot above is EXACTLY what you'll find on the site here.
Mark over at Mashable has no explanation for it, but I'm going to suggest the only obvious one I can think of: drugs. Acid to be precise, and lots of it. WTF doesn't even begin to describe this.