Then what is your definition of dummie?
I was always taught that calling others that was improper and rude.
He’s referring to Democratic Underground, which is a website. DU for short. The participants there are often referred to as DUmmies by FReepers.
It’s wise to lurk for a period of time before joining a discussion group and beginning to post. Apparently, you didn’t do that before you started posting here, and as a result, you don’t understand a lot of things that are common knowledge here.