Welcome to the thread called Oooops did I do that? Here, we the posters do the most ridiculous and terrible things, most of which have horrible global consequence. The first poster states what horrible event will occur. The scenario should be silly and with horrible consequences. They then use the spoiler tag to state what event the next poster must have done to cause the event to occur. The spoiler tag should be something fairly common in order to have it happen.
The next poster first opens the spoiler of the previous poster. If they did do what the spoiler says, they must begin their post with "Ooops I did do that!" If they didn't do what the spoiler says, they start their post with "I did not do that!"
The new poster must then create a new horrible consequence for the forthcoming poster in exactly the same manner. They create the event, create the spoiler, and the thread continues in this manner. Eventaully, those of us who "did do that" will be able to claim responsibility for the most horrendous things the earth has ever seen.
Confused yet? Here's an example....
The United States governement has a secret project in the works to eradicate all of the goldfish in the world that live in fishbowls.
Ooops I did that! (Yea, I just woke up, so sue me!)
A comet strikes the Chicago at percisely the required angle to knock the earth off its axis and plummet into the next ice age which lasts 20,000 years.