I think my favorite thing of all time was in a young MMO, reaaal young, the first boss raids were getting started. There was a glitch-- similar to what caused the Falador Massacre-- but it was only possible if you were a member of a specific faction, and futhermore, a specific guild subset of that faction, which was (according to the gimmick of the MMO) run by players. A friend of mine, who was there since the beginning, had established a deadlock on the rather obscure guild, and so it was just him, me, and a whole bunch of cronies. Now, y'see, the PvP areas were defined by this thing called a 'dark barrier', which had some boring fucking lore no one cares about. Inside, there was a specific effect, just like Runescape's PvP effect, which was literally defined by 'inside dark barrier'. There was a glitch that had existed in a relatively benign manner for a while, in which teleportation skills could be used with coordinates to push objects around small distances, which caused a variety of amusing but generally harmless bugs. One of these bugs was that items with rounded collision meshes could intersect players and be 'carried around', which would subsequently cause a variety of dumb shit that usually led to said player character being splattered all over the floor and looted by his friends. Now, if you had at least ~four people, you could carry a circular collision mesh roundabout anywhere, but it was very difficult to coordinate this properly because the in-game coordinates for most spherical objects were so fucking [b]wacky[/b], unless you had specifically placed the object in a way that makes the coordinates easy to extrapolate from each other. Let's go back to the guild, for a second; their whole gig is being the sneaky magnificent bastards, and they had a teleportation spell that would only work if it were to lead to a subsequent object theft, which had to be of a certain value. The leader of our guild had built an outpost of the guild with a training PvP ring, with a circular dark barrier, with easily-memorized coordinates, and a respawning loot object (that just barely met the value requirements) next to it. This item could be respawned rather quickly by private-messaging a bot in the area, because it was necessary for a quest that would unlock the training ring, which was (normally) in use constantly. For the third part of this event, there's a final glitch you need to know about, which involved using trading requests to quickly cancel out teleportations after you had already entered the requested position, sending you directly back to where you started. The fourth part relies on auspicious timing; there was, at the time of this story, a server-wide event going on, in which high-level loot was being distributed throughout the major town areas for people who could quickly kill swarms of low-level mobs or high-level bosses, restricted with some pretty ingenious administrative code that had prevented earlier kiting bugs from being used to kill the server. Overconfident as usual, the mod teams had left the server we were in, to check on the others, leaving a gap in the shifts that was a relatively peaceful 'dead zone'. So, no-one's in the training ring, my leader friend had left me in charge in his absence, and I had five lieutenants with extremely high-level loot, who had recently gifted me (in a rather Norse ceremony) an entire set of godly, fire-elemental-style weaponry that I was rather eager to test out. The six of us made a few macros to teleport and send trade requests, with a private constantly flooding the bot with respawn requests. After a few failed attempts, we suddenly teleported into the middle of town, with flaming swords of great darkness in hand, and an invisible 'dark barrier' surrounding us. As a final note of context, all six of us had recently done name-changes-- to Keital, Jodl, Raeder, Guderian, Rommel, and Manstein.

After six hours (unexpected server instability caused delays in logins, stopping moderators from getting through the flood of voyeurs interested in watching all hell break loose), twenty people were banned, with the stated reason being 'THIS SERVER IS UNDER THE TREATY OF VERSAILLES, [b]WEHRMACHT[/b].' During the raid of the main streets, we had used a few more macros to steal and delete any loot we had found. Unfortunately for the administrators, they had recently stopped loot-dropping exploits by simply obliterating any and all items deleted from inventories, and while the policy was subsequently reversed in favor of a more proactive approach, the damage had already been done; our high-level, high-damage unit had carved through the most populous neutral zone in the game, racking up a casualty number that would be impressive without context, and destroying multiple pieces of extremely valuable armor (a few of which were near-unique, or had almost been lost to time). A swift exodus of players made the game unprofitable, and in a few months, it had closed, with the final blog post stating that it had suffered the first "MMO Holocaust".

Now, if you're wondering, 'where did the other 14 people come in': one of the bugs caused by the teleportation glitch was that a copy of the collision mesh (that, with certain effects, retained its properties) was left in the original spot, where we had posted the code for the macros in a copy-pasteable format. Soon after the original group had really started picking up steam, a few more fell in, named after random ranks in the SS and Wehrmacht, with the 'leader' termed HonoraryGoring.