He is such a kook.

I saw a kookaburra sitting on the branch.

I found a kopeck on the street.

I need to exchange my dollars for kopeks.

I climbed to the top of the kopje to enjoy the view.

I sat on top of the koppie and enjoyed the view of the surrounding landscape.

The Koran is the holy book of Islam.

I want to visit Korea next year.

I am learning Korean.

I exchanged my dollars for koruna at the bank.