Why don't I understand the forum slang "troll"??
"Trolling" is a technique used in fishing where baited lines are drawn through the water behind a boat. Unlike trawling, which just uses a big net, trolling relies on the fish chasing the bait and getting hooked.
The forum term basically comes from that. A troll is someone who makes deliberately inflammatory comments in order to bait regulars and draw them into a fight. If you ignore them, they go away. If you don't ignore them.. well, these threads happen.