Q: Where does satisfaction come from?
A: A satisfactory!

Explanation: Satisfaction is that feeling you get when things work out.  I think of it as a feeling of calm joy because life is good, if only for a moment.  There are other meanings of satisfaction, and the Rolling Stones sang about not getting any.)

A factory is a place where things are made.  There is also the Cheesecake Factory, which is not really a factory but they do make cheesecake.

The word satisfactory means that something is OK, acceptable.  It is not great; it is not awful.  It is satisfactory.  A grade of a C is satisfactory school work in many places in the United States.

This joke is funny because it plays with the words satisfaction and satisfactory, as if you can make satisfaction in a factory.

If you would like to learn more about factories and the Industrial Revolution, the BBC has a bit of history for you: