Could someone write down a very simple basic example in javascript to conceptualize (and hopefully make me understand) how the jQuery plugin design pattern is done and how it works?

I'm not interested in how creating plugin for jQuery (so no jQuery code here at all). I'm interested in a simple explanation (maybe with a bit of Javascript code) to explain how it is done the plugin concept.

Plz do not reply me to go and read jQuery code, I tried, but I it's too complex, otherwise I would have not post a question here.