Pokayoke is a japanese word which means mistake proofing. It was coined by Shigeo Shingo as a part of toyota production system.
You will get clear idea about pokayoke with some of the examples:
Pokayoke Applied on USB Cable:
You must have seen the USB cable or pendrive when you insert it in laptop or computer then it gets inserted only in one way.
The other fine live example would be the sim card that you are using in your smartphones.
It is given a slant chamfer at its one end. So it would compulsarily fix in right position only.