Being an animal can sometimes be a little bit frustrating...the African bush is full of biting insects ...and reaching those out of the way itchy spots can get tricky...

Rhino's have their own scratching posts
…rocks are rubbed smooth after years of use.

The rough bark of trees also works well

 
Animals will use trees and rocks to scratch themselves.
Some will soak themselves in mud, wait for it to dry then scratch it
off to get rid of pesky insects.