I had to smile when I read this on Wikipedia. I'm sure that we have all met somebody who is an expert in this art:
Cowboy Coding is a software development methodology without an actual defined method – team members do whatever they feel is right. Typical cowboy coding will involve no initial definition of the purpose or scope of the project, no formal description of the project, and will often involve one programmer. It is characterized by a single programmer jumping into the writing of the software often working from his own idea of what the software should do. It is often characterized by a lack of any documentation for either the requirements of the project or the design of the software overall.
Read the rest on wikipedia: http://en.wikipedia.org/wiki/Cowboy_coding