I'm particularly fascinated by Microspeak terms which nobody actually knows the meaning of. You can defend jargon by saying that it's a shorthand way of talking in order to improve communication, but if nobody actually knows what it means, the in order to improve communication part is completely turned on its head. The Microspeak that allegedly allows people to communicate better ends up making them communicate worse.

A colleague of mine introduced me to this new type of Microspeak. Our conversation takes place in an impromptu hallway meeting between the development manager and a few members of the team.

Team member: "What does this mean for our milestone? I'm assuming it means that our features are code complete."

Development manager: It means you are pencils down.

Team member: (confused) "What does 'pencils down' mean?"

— It means your features are done for the milestone.

"Where did that term come from?"

— A meeting with «senior executive».

"Okay, so what does 'done' mean?"

— It means you are pencils down.

"What exactly does that mean?"

— It means you don't have to write any new code for your features.

"Oh, okay. So it means code complete."

— No, that means something different.

"How are they different?"

— I don't know.

"Has anyone sent any email defining what 'pencils down' means?"

— Not that I know of.

My colleague has yet to find anybody who can provide a definition of the term pencils down.

This sort of confirms what my colleague Michael Grier mentioned in a comment: The intended purpose for this jargon is not to communicate with the people who work for you but to impress the people you work for.