You Know What Meaning
(idiomatic) A phrase used to get someone's attention before announcing something.
Example: 2001 May 10, "Blake's Attorney on Bakley's Murder", CNN Live (transcript)
Well, you know what, he's got a cloud over him. You have to live with who you are and make your peace with your maker about what you really are.
2009 March 23, Alex Hawgood, â€œThe Three-Ring Circusâ€, New York Times:
Well, I guess Iâ€™ve got to say, I love the Madonna one that we did â€” the Drowned world tour. Actually, you know what? The first Blonde Ambition tour I loved. The â€œVogueâ€ thing â€” that was a memorable moment in my lifetime.