Sorry, I always had it drilled into me when I was young that I forget it might be be a common phrase. KISS is an acronym for "Keep it simple, stupid". Depending where you read about it, it was a design principle noted by the U.S. Navy in 1960, or by an engineer for the Lockheed Skunk Works, Lockheed Martin's advanced aircraft development program. It can also stand for "keep it short and simple" and "keep it simple and straighforward". Basically it just means that simple is a better way to go, as sometime we like to make complex systems when a simple system would do and be easier to maintain. Thanks for asking.

Jason