Parodied hilariously by College Humor in this video. Which has, ironically, started flame wars in YouTube comments on "We Didn't Start the Fire" between College Humor viewers and Billy Joel fans.
Half the fun of visiting 4chan, where it tends to vary between "Flame War" and "Troll War".
A great, and relatively new one, is a the Digg.com vs Reddit.com war. As well as Reddit vs 9Gag
And whatever you do don't compare any of them to 4chan or claim they're better than 4chan. Just don't do it.
GameFAQs' "Adult Swim" Board has one major rule (above even the site's rules), saying ANYTHING about Tim And Eric is a declaration of war.
Similarly, go to the Tales Of Symphonia board and make a topic about who Lloyd would be with (Lloyd x any character who appeared in the game).
The mere mention of a certain girl whose name refers to a three dimensional container with six sides warrants your being perma-banned from the internet, and the planet. This statement may have been enough...
Here's something that you might want to try out. Look for a forum (preferably showbiz-related) that has a fairly large Filipino membership. Create a thread titled "Kapamilya or Kapuso?" Talk about network ratings, and watch Armageddon unfold right before your eyes.
A little broad to fit anywhere else, but digital piracy as a whole. There's a reason the page pertaining to the issue has been locked out of real life examples.
Can sexual or violent genres of literature, anime, Western Animation, etc. have a bad influence on the development young children or not? It's best not to ask this question on any social network; it's as good as declaring war.