Trolling, in its most basic form, is basically telling a joke that makes people hate you. The less people that actually recognize that it's a joke, the more successful it is. On 4chan, most people label a "troll thread" with the phrase "you be postin' in a troll thread," or something of that nature. On other sites, it is less easy to identify. Take this for instance.
When I saw this post, it was on the first page, so it was fairly new. I knew however, that this was instant troll-bait, proven by the fact that it had many more comments than the other recent ones.
"Gotta brainwash ‘em early yeah?"
-The one quote to start the flamewar.
As my friend says, trolling leads to flaming, which leads to more trolling. To be honest, I can't really tell if this is a troll or not, because sadly there are people like this. Moreover, many people on sites like this aren't exposed to as much trolling as someone who goes on /b/ for instance. Trolling the unsuspecting is always a sure shot. While I don't completely agree with his viewpoint, I give him high marks for excellent trolling.