I should cocoa!
dated No way; there's no chance; you must be joking; I think not. From rhyming slang of the sarcastic phrase "I should say so," meaning the same. Primarily heard in UK. Bob: "So, are you going to finally join us for some karaoke?" Janet: "I should cocoa!"
I should cocoa (or coco)
I should say so. British rhyming slang 1996 Melvin Burgess Junk He said, ‘Someone'll really buy it and it'll be theirs then.’ ‘I should coco,’ I said.