Bumping it back to the front of what?
It is really a "bump" to the top. (of the list)
This makes the thread appear steadily in the "latest posts" category on FR, also keeps a thread from being moved to chat. BTT is the abbreviation. "Pinging" will cause the "my comments" spot on your personal page to change to "new posts to you" so you can return directly to the thread where you left off.