From Longman Dictionary of Contemporary English(it’ll) be curtains for somebody/something(it’ll) be curtains for somebody/somethinginformalFINISH/COME TO AN END used to say that someone will die or that something will end → curtain
Examples from the Corpus
(it’ll) be curtains for somebody/something• And will it be curtains for Coombs in Swindon?• But does it have to be Curtains for you and me? 