What was the Falador massacre?
The Falador Massacre occurred on June 6, 2006, when a player got 99 Construction and decided to have a party. When he kicked everyone from his house, he found he had the ability to PK players everywhere, without them being able to attack back. He was able to PK many expensive items, such as party hats. He has since been banned. You can find videos of it on youtube.com.
This is a good explanation, but I can also explain it because I happen to have been there, so I can tell you from experience.
I was standing around in Falador when all of a sudden my computer started to lag up. Because I had a MAC OS X, It quickly recovered, and I found, to my horror, people attacking each other, one user I can remember doing the most damage was called Durial321. What scared me the most was I had some pretty expensive items on me, and I wasn't in a PVP world. And yet here this random person, which I had never seen him before, was going around killing people, and the other people couldn't attack back.
A little side scene here
---I found that the cause of the glitch was a player having a house party shortly after gaining 99 Construction, which at the time, was a very new skill, and they had been the first person to achieve this. He had a massive house party...TOO massive, and it caused a lot of lag for him. Eventually, he had to boot everyone there, and they all ended up in Falador. BUT! The people who were inside of the Combat Ring inside of the house had a very unfair ability: they were able to attack anyone in the world, but the other person couldn't retaliate back. The only people who were able to attack was those who were inside of the Combat Ring when the user expelled everyone (it was also thought that people in the dungeons (not to be mistaken with the skill dungeoneering, but the Dungeon inside of the players house.) were also able to attack, but this was unconfirmed) OK, back to the story---
There was a large group of Player moderators who gathered in Falador, trying to calm everyone (Durial321 was in edgeville at the time, which I didn't know) i ran away, wanting to log out but curious to know what else happened. I found a long line of people, following someone and chanting "kill them!". I followed the line... and found myself face to face with this Durial321 person. He obviously noticed my armor, and I found myself in an unforgiving wave of Ice Barrages. I had my Anti-Mage prayer on, and I tried to run away. Several people were following me, mocking me and saying "you're going to die noob!" (i found this offending, due to the fact that I was about 5 levels higher than him, and yet I wasn't able to do anything about it.) I managed to buy some time by using Redemption, and I was healed, but then I was out of Prayer Points. Then, a MOD PMed me saying "Where are you? Do you know where Durial321 is?" (I was wondering how this MOD knew me, but then I remembered I was recommended to be a MOD, but I turned it down, saying that I wasn't ready for such a responsibility) I told him "south of edgeville, I'm under attack by him" I was close to dying, but then a J-mod showed up, and banned him.
The aftermath of this glitch was horrorfying, with many players killed unfairly and items that Jagex were not able to replace. Though this glitch has been patched and anyone abusing it banned, this casted a sad and upset shadow over the Runescape community... and was then on known as the Falador Massacre.
That is my story.