"Trolls" are users who sign up simply to flame, spam, and generally annoy others, no other reason. They start threads saying how great they are/how stupid others are, and just pointless stuff like that. To simply sum it up, "Trolls" are users who are looking for trouble, and will often start it themselves if they have to.
When people say "Don't feed the Trolls", they mean don't post in the thread, just in case anyone was actually wondering. By posting in their thread, you are giving them exactly
what they want. Attention. If no one actually replied to Troll threads, they'd simply drop to the bottom of the page and beyond. But instead, people reply, and it keeps the thread on the first page. And, even if the Troll kept constantly bumping his own thread, so what? It would be the online equivilent of talking to yourself...
So, three easy steps: Stop, drop, and er...
1. Report the post to a moderator, supermoderator, or admin, the last two are the best choices if available. Obi-Wan13, ACDCFanBill, and Rogue Nine are supermods, and Boba Rhett is an admin who is usually online. These are 4 people right there that would be good to message.
2. Do NOT post in the thread. Simple as that. Most Troll threads end up being bumped back to the top of the first page, by people posting in the thread, telling people not to post in the thread
The irony of it is simply amazing.
3. After the thread has been closed/deleted, just be on the lookout for another few minutes. There is always a possibility that the Troll may re-appear, so keep your eyes open. The mods/supermods/admins can't be everywhere all of the time, so help them out a little.
Remember kids, only you can prevent Troll Attacks
EDIT : Seems everyone already beat me to it...
And Rogue Nine brings up an interesting point. It does seem like a good idea to stop that user from retaliating, but perhaps a friendly PM(or an instant message from a messanger service if you know the user)would be a better choice than posting in that case. But of course, there will usually be at least one "DON'T FEED THE TROLL!!!" post in every troll thread, so if you feel it's really
necessary do what you think is right. We obviously can't stop everyone from posting in troll threads, and we're not responsible for everyone, but don't encourage a troll by posting in his thread unless it becomes really necessary. And of course, these are all just suggestions and ideas, we don't control everyone on the boards, and we don't control everyone in LFJA. So just use your own discretion, ok.