Portland pays more to keep this fucking dumbass elephant happy than to keep their public schools up to snuff. It takes a certain kinda backwards sometimes...
My dog does this sort of thing. He'll take a ball (especially a squeky ball) and roll over it with his back. I always figured it was like rolling in killed prey.
Play is a matter of intelligence, and elephants are one of the smartest animal on the planet. I don't suppose there's a mammal somewhere too stupid to play, like some reptile-level intelligence. Without smarts mammals are just a piping hot meal.