These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Crowning Moment Of Awesome: The Battle of Blackmore took place in the historic haven for zombies and held out for two months. Caiger Mall was the survivor haven until November 2006, repelling two huge sieges before finally falling to a third.
Caiger Mall again in December of 2007 - Until the new updates came. Technically, this was a CMOA for the Eastonwood Ferals, who breached the barricade and managed to keep it open for the others to get in, but all of the (undeserved) credit went to Kevan and his zombie buffs, which resulted in a great deal of human players leaving - and with them, the zombies, after the suburbs got empty.
It should be stated that CMOA's in Urban Dead tend to run both ways. For instance, for the zombies the fall of Caiger, Blackmore, and so forth was the awesome part.
Every day for two months was a CMOA for the Blackmore survivors, and the complete opposite for the zeds. The fall was just a return to the status quo.
As far as we zombies are concerned, expelling the invaders from our homeland was most certainly a CMOA.
Dude, Not Funny!: "Text rape", a particularly nasty form of griefing in which a survivor goes up to a group, names a character from that group and graphically describes the rape of the chosen victim. It's something that many groups object to very strongly, even zombies and PKers, and text rape is now considered such a crime that you can be blacklisted at revive points and PKed just for doing it. It sparked a petition to ban text rapists on the wikia and forced Kevan to implement an "ignore" feature, since banning the text rapists is easier said than done.
Fanon: On the wiki, to the point where the line between Fanon and Canon has become blurred.
Part of the reason is that the backstory to player characters and organizations is treated equally to actual Canon backstory.
Game Breaker: An exploit based on the way combat and search rolls were calculated used to allow players with careful timing to create "chains" of hits; after trying a few times and hitting once, if every subsequent attack made done exactly eight seconds later you would hit with every one (how exact you needed to be depended on your chance to hit). Fortunately, this has been fixed and the die rolls are now actually random.
Internet Backdraft: Go onto a human-dedicated forum, and mention zombies reading graffiti. Bring a helmet.
Hell, bring a fire-retardant suit when you suggest anything on the suggestions wiki. They do not play nice.
For that matter ANY of the big survivor forums are constant sources of Internet Backdraft. The zombie forums not so much.
Barhah.com has been filled with people bitching about human benefits and low attack rates, until Kevan tipped the game in their favor a lot.
DEM. Hated by PKer groups (because the DEM used to maintain the "official" bounty list and its own team of bounty hunters) and a few survivor groups for reasons unknown.
Reasons unknown? Read this. Mainly, they hate the DEM because they used to allow character alts in their different branches and use auto-scouting tool, both of which are considered borderline cheating by some of the community though not by the game's creator. Also, many local pro-survivor groups in each suburb use their own barricade plans. They see DEM's attempt to implement the wiki listed barricade plan as Fascistic.
In general, almost any general forum for the game will be filled with deliberate dickery from the mods on down. There was a brief period after the demise of the original Desensitized where a couple of forums were hit with the "This is not Desensitized" call for civility, but this died a painful death.
Memetic Badass: Petrojsko, the original leader of the RRF, gets this a lot. So do a few other old-timers who have been very, very successful at the game.
Memetic Molester: ALSO Petrojsko, whose profile proudly states that he is wearing no pants.