Normally, Niko cannot kill his dates, but only "scare" them. When on a date with a girlfriend or boyfriend, have them follow you to any coastline. Swim out into the middle of the ocean. A few yards in the water, Niko's date will instantly die. Note: This glitches the game. If Kate gets killed, her telephone will always be busy when called. Niko will also receive date invitations from dead people labeled as "Unknown Caller".