Any member of an internet message board who is contributing unsolicited and unappreciated posts to another member's thread with the unintended result of "bumping" the thread to the top of the list of threads each time and thereby keeping the thread current and potentially popular.
"Man it really annoys me when he replies to my threads. I wish he'd go bother someone else. Oh well, at least I get bumped to the top everytime he does. He probably doesn't even realize he's my bumpmonkey."