I have a fascination with language. Half of my job is communication (isn't half of everyone's job communication?), so I am always thinking about how well language works.
One of my colleagues was explaining our various administrative systems to a new hire. After several minutes of explanation, he wrapped up by saying "that's it in a nutshell."
Now, this just seems like a bad metaphor. Granted, a nutshell is a small container, but just about the only thing you ever find in a nutshell is a nut. What is complicated about a nut? When someone says "that's it in a nutshell," aren't they usually talking about condensing some big idea, or complicated info, into something small?
So here's my idea for a replacement metaphor:
"That's the whole ship in a bottle."
Try it out at your next dinner party.