Official Rules of the Game:
(i) If you think of the game, you lose.
(ii) If you lose the game, you must announce it to the people in your vicinity.
(iii) Once a loss has been announced in your vicinity, you have 30 minutes to forget the game before it resumes.
(iv) If someone asks, you must explain the game to them.
(v) For the purpose of KirupaForum, if you lose the forum, you must post in this thread to announce your loss.
Now that you know the rules, you are automatically playing whether you like it or not. My dorm floor has been playing for several years (and I personally for over a year). And after doing some research, it is not just us. In fact, there is a website devoted to the game that I found while trying to find more information on it.
A proposed (but not widely accepted) rule is that the game will come to an end if/when the current acting Prime Minister of Britain announces on live television that he/she just lost the game.