He said he'd give me a job if I passed my exam with a grade A. A fat chance I have of that! Oxford Idioms
Fat chance of us running into any crumpet out here! BNC
Right now, though, these fine sentiments have got a fat chance of being put into practice where I'm standing, boiling the milk for yet more midnight cocoa: with a baby of six weeks in the family, the philosophy of parental detachment is a far cry from reality. BNC