"Bullet proof can be used to describe of an algorithm or implementation considered extremely robust; lossage-resistant; capable of correctly recovering from any imaginable exception condition -- a rare and valued quality. Implies that the programmer has thought of all possible errors, and added code to protect against each one. Thus, in some cases, this can imply code that is too heavyweight, due to excessive paranoia on the part of the programmer.
i.e "Peter Lewis's code is 100% bulletproof"
Source - http://Dictionary.com (Jargon File)