"Nothing:" Code Word for "Boobs"

Dave and I have this ongoing conversation - that goes something like this:

Kell: What are you thinking about?
Dave: Nothing.
Kell: What do you mean, nothing? Do you really mean that your mind is thinking of nothing - no thoughts - no pictures - no mental conversations?
Dave: Nope. Nothing. Don't you ever think of nothing?
Kell: Nope. My mind is always spinning.

Well, today, My friend Mark and Dave and I were having breakfast together, and the same topic was discussed:

Dave: Kelly can't fathom that guys can sit around and think of nothing.
Mark: We can.
Kell: I just can't believe it. No one can think of nothing.
Mark: Well, honestly? We're really thinking about boobs.
(Dave smiles and nods)
Kell: Boobs? Whose boobs?
Dave: Only yours honey. There are only two boobs in this world...
Kell: Yeah. And I'm having breakfast with them right now.