F.I.I.K

Acronym for Fucked If I Know. A possible reply to be asked a question regarding a matter outside one's field of training or experience or actual interest. Usually used in exasperation at the pointlessness of the inquiry.

Office Girl : Oi, there you are. So what does this F.I.I.K you keep putting in the delivery time column actually stand for?
Truck Driver: Fucked if I know.
Office Girl: No need to be rude about it ya prick.