you know who/what
you know what
1. A phrase used to convey a realization, often mid-sentence. I wasn't going to go out with you guys tonight, but hey, you know what, I'm in!
2. A rhetorical question posed before a statement one considers to be the blunt truth, often during an argument or heated exchange. You know what, John? I think you never really loved me.
3. A statement asserting that the person to whom one is speaking does in fact know something that they claim not to. A: "What is the matter with you?" B: "You know what!"
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
you know ˈwho/ˈwhat(spoken) used to refer to somebody/something without mentioning a name: I saw you know who this morning. She didn’t even say hello to me.
Farlex Partner Idioms Dictionary © Farlex 2017