If you know you know

I come not to bury this phrase but to praise it. I thought it was another content-free incoherence that could be mumbled in any context, like It is what it is, You already know, or that eighties classic, Whatever. I was a fool. Iykyk implies knowledge that only experience can bestow, that words can't fully describe, and that others without that experience can't fully comprehend. It communicates respect for that experience and offers a sense of connection with those who share it. The deep knowledge. If you know you know.