It's كرمال الله kermaal aLLa (approximately), and it's probably etymologically from كرمًا لله 'in honour of God' (or something along these lines). But you're right that it translates as 'for God's sake'.
Off the top of my head I can't think of a situation in which a weaker translation is more appropriate. When I hear people say كرمال الله in normal conversation it's 99% of the time exasperated or angry and carries exactly the same connotation as 'for God's sake!' But it's sometimes used by beggars in a different tone as part of a general repertoire of religious invocations, in which case '[give me some money] for God' or a lighter 'for God's sake' might be appropriate.
كرمال is a (in most places less common) synonym of عشان, مشان etc. It's particularly commonly used in Lebanon and the coastal areas of Syria.
Thank you so much Analeeh for both your spelling correction and meaning /examples .
Indeed, the mood of the person who says /writes كرمال الله is exactly what I needed for a better understanding