troll: someone who intentionally posts derogatory or otherwise inflammatory messages about sensitive topics in an established online community such as an online discussion forum to bait users into responding.

Trolls are inevitable. Open up an online forum, they show up and, like your drunken uncle or abusive big brother, make fun of all you hold dear. Trolls are why comment spammers are so annoying to people like me. At least trolls are somewhat on-topic! Comment spammers will just vomit random words and links for Viagra and porn all over the Inter Tubes.

As with all forms of humor, it’s quality that counts most. Trolls are usually childish and stupid. In a bad way – Sometimes, childish and stupid is exactly what’s needed. When you see eye to eye with the troll on the ‘dumb-ness’ of a forum, it can be comedy cold: Getting banned from the My Little Pony forum

And since we’re talking about My Little Pony, it would be a shame not to include this: