3: Patch 3.0.8: For those of you who don't remember, two words, Lake Winterfail. The patch that brought Death Knights to the unwashed masses also brought a glitch which caused the entire continent of Northrend to crash for 5 minutes whenever the Battle for Lake Wintergrasp ended. When Northrend came back up, the Wintergrasp began again, meaning that Northrend was only up for about 15-20 minutes at a time. Players earned an astonishing amount of marks, being able to do WG every 20 minutes, as opposed to every 2.5 hours. Epic marks, epic honor, epic annoyance.
2: Patch 3.1: My personal favorite post patch anecdote comes from the Secrets of Ulduar patch. The Tuesday that it came out, I was part of a ten man guild expedition into the titanic facility. I took the helm of a siege engine, steam rushed down the ramp, and fell through the world. As many have done since, it's a known bug. But here's where it got interesting. I landed. In Naxx. In Grobbulus' room, to be specific. In my siege engine. What really made it priceless was the fact that it wasn't some new Naxx instance made for me... oh no, it was a Naxx in progress by a horde guild, who were getting ready to pull Grob. My tank lands right next to Grob, and pulls him before the hordies were ready. Hilarity ensues. I was so flabbergasted, that I just sat there in my tank. Then I realized the potential this situation had. I drove over and electroshocked their Grob tank, one shot, one kill. Now, the initiation of PvP combat inside of an instance must have broke something in the code, because once the horde tank died, the entire instance despawned from underneath us. We fell into oblivion, repeatedly, taking durability damage each time. I lost my siege engine after the first fall, took a screenshot, and logged off for a while. I logged on a few hours later to find myself in ghost form in Crystalsong Forest, with my corpse apparently buried far underground. I had to eat a spirit rez, and a nearly 200g repair bill from the dura loss from falling so many times, and the rez damage.
1: Patch 3.0.2: As fun as nuking horde raids with siege engines, and stacking marks of WG to the ceiling were, in terms of unmitigated fail, patch 3.0.2 took the cake. Echoes of Doom brought the scourge invasion, and for about two days, the servers were so unstable the game was practically unplayable. Servers crashed when people earned an achievement, took a point in a 51 talent, logged on... Basically, for a few weeks, while they were backtracking all the bugfixes, WoW was closed on Tuesdays.
So, when you're complaining that the ICC portal leads to Naxx, and that in order to get into ICC, you have to use the Wailing Caverns portal, or whatever way Blizzard tries to screw up 3.3, remember this, it probably won't be worse than what we've already dealt with.