Q: Where does satisfaction come from? A: A satisfactory!\nWhat do you think is the punchline of the above joke?
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: