Word expert James Rogers says the expression was common by the late nineteen seventies.

VOA: special.2010.07.25

The technical expression of that in philosophy is common knowledge, which I can never spell, so I'm going to wing it.

在哲学上叫做共同知识,我不知道拼写对不对,我看一下

耶鲁公开课 - 博弈论课程节选

Joe Blow is also an expression for a common man.

VOA: special.2010.02.07