Regarding slang helping having a secure conversation:
I was watching the Daily Show the other nite and they had some guy on there who did lots of investigation/journalism on the mob and he relayed phone tap conversations that went like this:
Mobster 1: You got the tee shirts we talked about?
Mobster 2: Yeah I got them tee shirts.
Mobster 1: So how do the tee shirts look?
Mobster 2: They are really white, I mean the whitest.
Mobster 1: Yeah? I'm going to pick me up some of them.
Mobster 2: These tee shirts are the best we've had in while.
Mobster 1: Alright, put me down for three and a half tee shirts.
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Mobster 1: Did you get the things?
Mobster 2: Yeah I got the things.
Mobster 1: You gonna bring the things later today?
Mobster 2: Yeah don't worry, I'm bringing the things later today, don't worry about it.
Mobster 1: Good, Jimmy really needs to get his hands on the things.
Mobster 2: Tell Jimmy not to worry.
Mobster 1: Oh, and don't forget to bring bullets for the things.