This entry isn’t the best, but because I’m still IP blocked I can only use my phone to write, and the content I can add is rather limited.
06-06-(20)06 - RuneScape's day of infamy. Or RuneScape's most exciting day. Depends on who you ask.
6-6-6 was the day the Construction party bug took place, and a then rather unknown player - Durial321 - became the stuff of legend. I could explain what happened in my own words, even though most people probably remember the whole thing like it happened yesterday, given how shocking it was at the time. But I'll let your own and only @Adam? tl;dr it to you:
2007 Adam? is completely right. The Falador Massacre was caused by a combat ring bug in Cursed You's house. Cursed You was an insanely rich player, who invested his many resources into becoming the first player to ever achieve 99 in the then extremely expensive skill Construction. To celebrate this fact - like any rich person would - Cursed You threw a gigantic party at his PoH and invited the entire game to attend. Things went sour when Cursed You decided to expel the many players inside his PoH, causing a malfunction in the house itself and the game. Players in the house's PvP area - not all but only a select few - found themselves able to attack people outside the PoH's instanced area. A dream come true to any PvPer.
One player in particular took advantage of this: Durial321. He began slaying people left and right, killing them with a combination of deadly Ice Barrages and his Abyssal Whip (back them still the top weapon). Players caught and killed dropped all their valuables, allowing Durial to loot two already then very expensive Party Hats, including a Green Party hat Durial then wore as the ultimate middle finger to the people he was killing, as seen in the video footage.
After a few minutes of complete and total mayhem, Jagex staff finally intervened and disconnected Durial321, and banned him for bug abuse. By then damage and been done and RuneScape history had been written.
in 2016 Jagex hosted events celebrating this infamous day, with multiple references to Durial321, Green Party hats, and a NPC version of Durial for players to fight.
The original Massacre video: