A 'Kill', or 'Kills' refers to the amount of Females or Males a
person has had sexual intercourse with. Essentially their "Body Count" or "Kill Count" so to speak.
It's also a fairly more discrete way to let your friends know how many Females or Males you've been with, without letting everyone know.
A Female or Male can refer to their 'Kills' it's not
single gender oriented.
Guy 1: Dude! I just got another kill last
night.
Guy 2:
Sick man, that's what? A body count of 6?
Guy 1:
Yeah dude, I'm slowly piling the bodies up!