A way of saying nothing implying a negative tone, usually of agravation. Generally used when some one is bored and wants something to do or if some gave a lot of effort for no profit.
Guy 1: Hey man, what are you up to?
Guy 2: Dickfuck all, wanna grab a beer?
Girl 1: How much did'ya win at the casino?
Girl 2: Dickfuck all!