My current hypothesis:
When someone posts to a thread with the word bump as the opening or sole word in their post, they are trying to revive interest in the thread by having it go to the list of new postings.
Or they may be wanting to attract the moderator’s attention to the thread because they think it’s bending the rules of the board too far, and someone needs to be bumped OFF the board, or the thread bumped DOWN to the Pit?
'Zat right? It’s the result of a month of puzzling.
Redboss
Your first hypothesis was correct. Every time a thread is posted to, it’s “bumped” to the top. When people post to a thread with the sole purpose of “bumping” it, they simply say “bump”… well, the uncreative ones do, anyway. 
Dang! Spoof beat me to the answer, and it was a simple one too… 
The least I can do is BUMP ya up though
— Raven
Thanks to both of you.
Redbump
hehehehe
I feel I understand it now.
RB
By jove, yes, I’ve got the gist of it, as it were.
Undeniably got the hang of this “bump” phenomenon. Thanks everybody.
at this thread MysterEcks says
And I though I was being so cute and funny. I was planning to spell out BUMP with the initial letters of each post and everything. Now I feel like a naughty nine-year old boy who’s just been caught stealing money from his mum’s purse.
SORRY.
I’ll just go to my room for a few days.
[sub]bye. see you Thursday.[/sub]
Redboob
It should also be noted, by the way, that if you do think that a poster needs to be “bumped off the board” or a thread needs to be “bumped down to the Pit”, the proper procedure is not to post anything in the thread at all, but rather, to e-mail one or more of the mods or admins. This way, if it turns out that the person is innocent, they don’t have to deal with excrement being flung all over the boards at them.
Don’t worry, by the way, about the breach in etiquette there… We all have to learn these things some time, and it’s better to learn it now, while you’re still somewhat new, than to screw up when you’ve got a few thousand posts and everyone thinks you should know better.
grind
test
the screen says I’m not logged in. I was trying to e mail this page to someone. testing…
The “e-mail this page to a friend” option has been turned off because of abuse. We’ll see if we can get rid of the button as well, as it only creates confusion, apparently.