Zero-sum gain or fingernails on a chalkboard time

The phrase 'zero-sum gain' is like fingernails on a chalk board for me. I just read it on a worksheet handout for an upcoming RWA workshop on Professional jealousy. It is a common error of the English language and shows that the person using the phrase doesn't know what it means and is simply throwing the words about -- a malapropism.
The actual phrase is zero-sum game. Specifically, the phrase describes a type of game in game theory. I had to do game theory when I did my econ degree so indul...