Everytime there is a new post to a topic it "Bumps" the topic to the top of the list.
Bump is for when the author still wants/needs responses and wants to move the topic back up the list. There are allowances for Bumping topics in the forum rules, perhaps you should read them.
Also, Bumping is not annoying. Annoying is people creating another post with the same topic and not bumping. And almost as annoying is people Spamming other peoples topics with posts that have nothing to do with the topic.
Now I am guilty as charged for spamming. Sorry about that Bone, consider it a free Bump.