It's hilarious. And it's really not to be taken too seriously or over analyze. It's funny as befitting Djokovic's personality. Even though he had vowed to be more serious after the slam win, quitting players imitations and all, but a zebra can't change it's stripes. He is a funny guy and really don't mind hamming it up. Can't imaging any other player doing this and pulling it off.
Why so serious? It can't hurt to have a Djoker or two around.