Undercover cops talking?
One is trying to get the other to go "undercover" or work in disquise, where people don't know who you really are.
Guy #1:Say no and we never met and you start monday as joe rookie ("Joe Rookie" means ordinary beginner) . Say yes and you're on the fast track to a gold shield (promotion, higher rank). You'll never have to hose vomit outta the back of a squaddie.(probably THE worst job a cop has to do, noone likes to do this. Usually the lowest raninkg cop has to do this)
Guy #2:I'm whoever you need me to be.
Guy #1:I take your white shield (first badge) and lock it away with your file.
Guy #1: You'll see it again when you come in from deep cover.(return from your undercover work back to the squadroom. Deep cover means that no one knows where or what he is doing. He enters the world of the criminal and infiltrates that group)