This game is played by creating a parallel universe with one difference to this one. The next poster will then state the result due to the difference, and make his/her own universe.
Example:
User 1: There is a parallel universe where people greet each other by smashing their knees together.
User 2: As a result, humans are no longer able to walk. There is a parallel universe where men have breasts.
There is a parallel universe where the sky is bright red.
As a result, the sky will have gravity on you and you fall in deep space, an eternal nothingness!
There's a parallel universe where you can hide your car and other things in a small flash memory and carry it with you. No need for parking, packing, bags and etc.