When Pressing The F8 Button On Your Keyboard, You Activate fatality Mode. The Nearest Ped Will Have A Red Marker Over Theyre Head
And When They Die, You Will Here A "FATALITY!" Noise. Pretty Fun To Use Actually 

*EDIT*

a new bug fix has been added that fixes a bug found by angeloelibz24

BUG: *when there is no one near you the game crashes.