The wording is, though typically when I have heard it used (like when TheLoveTiger used it), it is out of genuine advice for someone. Like someone is making something unnecessarily complicated, and someone is saying to scale it back using the K.I.S.S. saying.
I believe I have heard 1-2 nicer ways of saying the last word or two, but I cannot remember them right now.... Maybe TheLoveTiger knows what they are.
Slindur