The reason of Bartholomeo Kuma's devil fruit named as Nikyu-Nikyu no Mi? Nikyu-Nikyu no Mi is devil fruit that eaten by Bartholomeo Kuma, this fruit can be translated as Paw-Paw Fruit.

The power of this fruit are it can repelling any attack, or pain from our body as we can see in Thriller Bark arc when Kuma repelling the pain from Luffy.
This fruit also can make other peoples flying for few days to somewhere place in the world.

What I'm ask here is what the reason behind a paw that can "repel"? Is there any myth or something that make this fruit named as Nikyu-Nikyu no Mi/Paw-Paw Fruit?
Paw-Paw fruit grants the user the ability to repel everything they touch, and is physically represented as paws on the user's palms, making the user a Paw Human. 
The Paw has variety of uses that leaves a paw-pad imprint resembling the pads on his palms. 


Cats uses one paw to repel inferior life forms. The Paw Of Do-Not-Want. Which might also be the reason behind a paw that can "repel" of your question. Video: https://twitter.com/boingboing/status/596558460382220288
The fruit's name, Nikyu, comes from the word "Nikukyū" (肉球?) which means "Paw" in Japanese.  Ref: Nikyu Nikyu no Mi
I did a little search online if there is a significant reason why its called Nikyu-Nikyu no Mi/Paw-Paw Fruit but I found none that its related to myths or something. So the name "Paw-Paw" is basically just from its Japanese name counter part "Nikyu-Nikyu".