They may not be the "code" that most of you know but it's an interesting story...

I've seen code on PLC's and embedded microcontrolers used in industrial safety applications that could have been lethal or at the very least, a finger eater. For about four years, I worked for a company that manufactured light curtains, hardguards and other devices that keep machinery operators from losing limbs.

The most dangerous "code" I've seen was on a large metal stamping machine. The maintenance department was using a PLC to take the anti-tie-down inputs and start the stamping process. The operators had tied one of the palm buttons down with black tape so they could hold the metal with one hand and start the process with the other. The PLC was also counting the inputs and cycling the machine to satisfy the counts whether the operators wanted it or not. Anyway, to make a long story short, our company was called in to install a light curtain and pitch all the other "safety" junk. The techs that mounted the curtain found a part of a hand behind the old physical guard.