I have been spending a fair amount of time on forums these days. One constantly confusing post that I would see is a single word, “bump”, with no other content in the post.
Finally, after seeing it today, I decided to look up the answer:
To bump a thread on an Internet forum is to post a reply to it purely in order to raise the thread’s profile. This will typically return it to the top of the list of active threads. BUMP is sometimes used as a backronym for “Bring Up My Post/Post count” or as a recursive acronym “Bump Up My Post”.
Thank you Wikipedia!