The act of getting "all 10's" from the judges. The perfect score in a beauty pageant, sporting event, or other judged competition. Being the fiercest queen. The ultimate kiki. Popularized in the film "Paris Is Burning" / 1980's NYC "voguing balls".
While someone who posts such a message will sometimes mean it and will never again go to that board after posting such a message, usually once they calm down, they'll come back and will be posting as though they never posted it.
On some messageboards, such messages are so common and/or posted by certain users so much that people have learned to automatically ignore them.
I logged inthis morning to find yet another I'm leaving the board forever message. The guy that posted it has already posted ten of them and returned less then twenty four hours after each time.