OK or fine. The word is shortened from kosher, a word meaning blessed by a rabbi. If something is kosher, it's acceptable, and kosh is simply short for kosher.
To be deliberately obscure or cryptic when telling a person something or answering a question. Origin: Kosh is the name of an alien on the science-fiction series Babylon 5. His speech was as described previously. The term has been used in the past by people on the internet familiar with the show.
"Stop koshing the question!"
"Just quit koshing it and just give me a straight answer!"