when Blizzard introduced a new dungeon called Zul'Gurub into the game as part of a new update for the game. Its end boss, Hakkar, could affect players by using a debuff called Corrupted Blood, a spell that damages players over time, this one specifically doing significant damage. The spell could be passed on between any nearby characters, and would kill characters of lower level in a few seconds while higher level characters could keep themselves alive. It would disappear as time passed or when the character died. Players could spread this effect by teleporting out of Zul'Gurub and passing it on to other players.
and soon people just kept spreading it like a viral plague....here's a vid of me spreading it in 05
i posted this for comedy reasons please don't spam