This is a statement every
man will inevitably hear in their
lives. It is stated by a
woman (in a serious situation) and usually mockingly by a man.
Women use this to
annoy,
confuse and
otherwise torment their men or men in general.
An example perhaps? Sure, here it is.
A woman asks a man something. He gives a non-commital answer. She asks a different, but underlyingly similar question. He wonders what she is asking. She pulls out the "hands on hips" thing and says those horrible words, "If you don't know, I'm not going to tell you".
The result:
The world sighs in sympathy. A flower somewhere dies. A white sheet on a bed turns a little darker. A lyricist discovers a new rhyme for his song. And the man in question becomes infinitly confused and just wonders why the Hell there isn't a female language translator.