A term used on imageboards and forums to describe users and members who have been there from the start.
With regards to /b/, they're the only reason /b/ existed long enough for the newfags to ruin it. We don't want to explain memes to you or guide you away from the trolls. If you don't want to be called a newfag, then sit back idly until you're accustomed to our way of life. Then, an hero.