I actually studied ninjutsu (Togakure-ryu) for a several years in the late eighties. The core of real ninjutsu is adaptability, not the movie-ninjutsu that apparently supported the "ninja coder" silliness.
"Like a mad Klingon" would be "Fire-style" in ninpo terms; direct, forward focused; make yourself into an "irresistible force", or as close to it as you can manage.
A real ninja coder would be someone with a wide repertoire of techniques and tactics and a deep understanding of his craft, and who constantly adapts his approach to the needs of the work.
I was just thinking the other day about terms like "ninja", "pirate", and "rockstar" that are so played out at this point they make me cringe whenever I hear them. Isn't there something fresh to convey the concept of being a badass? "Klingon" works pretty nicely. For now at least.