"a Van Dyke": leaving a scene, usually a party scene, early and then starting the next scene with a phone conversation which elaborates and expands the previous scene while also introducing new information. A nice bit of shorthand.
From, of course, the Dick Van Dyke show. You'd leave the party scene at the point of, say, Laura downing her third drink and Rob realizing she was out of control. You'd then come back to Rob on the phone the next day, talking to Buddy: "Yes. Yes, all of them. And a pony! What? The producer I'm trying to impress was there? Why didn't you tell me!"
Don't miss it.