Not many people know this but, I am a huge fan of this movie and this book. Since this happens to be less of a blog about movies and more on self help and software engineering, lets tackle the latter. Although, if you are feeling particularly bored tonight, do rent the movie.
Breaking shit! Alright, so guessing that you didn't pick up the book? Right, breakable toys refers to a piece of code/application/software that is near and dear to the your heart yet, perhaps not "mission critical" to the client. The authors of Apprenticeship Patterns (or AP for shortzies) talk a lot about building these toy systems in isolation, or private. I love this 'pattern' but, I think there exists a better spin to the whole design in isolation idea.
Design in production
We all have little problems that could be easily solved, quantified, or tracked using some kind of application. Focus that need and build a breakable toy. It doesn't have to be complex, or even all that great, just build it. Once it is finished, iterate by bringing someone on to help its inevitable design wonkyness or just keep adding features through user stories. The main verbs being: build, deploy, iterate, test and perhaps most important of all: break.
Well...most important of all might go to actually reading AP. Really, read the book, you can thank me later