Can someone please tell me what bum marketing is?

I keep hearing bum marketing this and bum marketing that. I've also heard that its a form of article marketing.
How would you define bum marketing?

You've got it nailed. Basics behind "Bum Marketing" are that you use articles to promote your books, affiliate links, website, what ever.

If you'll take the time to do a Google search for bum marketing you'll find that there's plenty of free information out there.

Pete