"TO 450!" was a meme created by TableFlip on the Pokemon X board during the The World Changes into Pokemon! RP.
MovesLikeJabba stated that he did not want to read the last 50 posts of each thread due to random visitors wanting to snatch the last post, so an idea was created that whenever the thread reaches 450, there will be a "non-canon" time in the RP. TableFlip then started posting "TO 450!" posts, and it soon became a trend for everyone to spam it whenever there was over 400 posts.
This Meme TodayEdit
This meme is rarely used anymore, with the exceptions to some RPs and CYOAs on Warflame where users would reference it during the mid 400 post mark. It's also used on threads that are predicted to get a lot of posts, such as troll topics or debate topics.