Clockers, by Richard Price

Here are two bad dudes talking about what they're not talking about (In case one's wearing a wire? In case one has to testify in court? Because it's gentlemanly not talk about crime directly?):

   "Got to be got," Victor said again, lightly pounding his fist. [...]
   "I know somebody who'd do it, too," Victor said softly as he returned to his inkings. [...]
   "What you say?" Strike stared at Victor in the mirror.
   "I said I know somebody who'd do it, too." He fixed Strike's eye with a fat, sober look.
   "Who?" Strike heard the hopefulness in his question.
   "My man." As if that explained it all, Victor's eyes dropped to his writing again."
   "My man who?"
   "This guy."
   "You know him?
   Victor fixed him with that cold, sober stare in the mirror again. "I said he was my man, didn't I?" [123]

A bad cop tries to get Strike to cut him in on drug sales:

   "But I got me a problem." Andre smoothed the top of Strike's head. [...]
   "Uh-huh."
   "I need me a sponsor."
   "Uh-huh." Strike kept his voice low, Andre beginning to scare him a little more now.
   "I need me a benefactor."
   "I hear you."
   "You hear me?" Andre strolled behind Strike again. "That's good, 'cause I could lock you up. Shit, I could even mess you up first, say you tried to fight me, you know what I'm sayin'? [...]" [287]

Some more "cop talk", updated from what appeared in, for instance, The Maltese Falcon, this time between Rocco and Strike. Rocco is trying to figure out of Strike is lying for his brother:

   "So when was the last time you spoke to your brother?"
   Strike sighed. "Saturday."
   "OK." Rocco nodded as if he knew it all along. But the answer threw him for a loop: he'd thought Friday was the last time, at the bar before the killing. "OK, where?"
   "In the projects."
   "What you talk about?"
   "Nothin'."
   "Nothing?"
   "That's about aw-all we usually talk about. We're not that close."
    [...]
   "Because I didn't want nothing to do with that. I figured if I told you that, then you'd be bringing me down for a statement. Next thing I know I'm helping to ha-hang him, you know?"
   Rocco found it hard to tell if the kid was lying: he was avoiding eye contact on everything, but his demeanor was distant, preoccupied, as if his troubles were all over the place. [533]