Fuck it or kill it. Ask yourself which hormone is primarily responsible for making someone want to either fuck or kill. Did you guess this one? If so, congratulations...you're right!
The phrase, fuck it or kill it, first appeared in the book A Brief History of Everything by philosopher Ken Wilber. "Testosterone basically has two, and only two, major drives: fuck it or kill it," alleges Wilber.
Sean O'Reilly, in his book How to Manage Your DICK, cites Wilber, but turns the phrase into an acronym: FIKI. The FIKI instincts explain why men tend to be more impulsive than women, he argues.
Evolutionary psychology, makes it pretty clear why we have these instincts. They help us to survive. Or, they used to anyway. The only problem is that, living in the society of today, we don't need FIKI to survive anymore. Unfortunately, it seems that evolution has hardwired us men this way. FIKI explains why murders and rapes are committed disproportionately by men, and not by women. Until our software catches up to our hardware, the FIKI impulses will continue to cause problems.