How do say kush in Japanese?

There isn't a direct translation for "kush" (referring to cannabis) in Japanese. Japanese doesn't have a single slang term equivalent to the English word. You would need to use descriptive phrases or loanwords depending on the context.

For example, you could use phrases like:

* 大麻 (taima): This is the formal term for cannabis, but it's not slang and carries a strong negative connotation due to its illegality. Using this term would be appropriate in a serious or legal context, not casual conversation.

* マリファナ (marihuana): This is a loanword from English and is commonly understood, but still quite formal.

To use slang, you would likely need to borrow English slang terms or create a new expression within a specific group, which would not be easily translatable. Simply using "kush" as a loanword might be understood in certain contexts, particularly among younger people familiar with English slang, but it’s not a standard or established word.