Why do they call Carribeans West Indies?

Columbus was searching for a shorter route to the spice islands that were known as the east Indies. The people of his era had no knowledge that there was another land mass between Europe and Asia. When he reached land in the Caribbean, he named the islands the west Indies. He didn't "think he was in India", he knew he wasn't. The Europeans had been trading with the people then known as Hindustanis for a long time. Columbus knew he had stumbled upon new lands and new peoples, and he immediately began to enslave them and force them them into trying to get him gold. 

Christopher Columbus attempted to find a short cut to India by sailing west from Europe. He landed at several Caribbean islands thinking it was India. When people learned these were actually new lands and not India, they referred to the new lands as "the West Indies."

the guy who called them that thought they were somewhere in relation to india

Because the discoverers thought they had found India.

Because indians owned it at one point kind of like how indians owned america at one point before white men stole the land from them.