I can do Terminator eyes too.
I get a sense of Fi when I balance a lot of human factors in a moment. I take in a lot of info and then weigh it all. My desires, others desires, the reality of it all.
Also I think it is the feeling I get when something doesn't feel right. A right brained flowing feeling where you just feel that something would look and feel better another way.
I have come to the conclusion that because a lot of isfp's talents are so subjective a development of unbridled cockiness is not only desirable but necessary in order to be successful.