PC's discover secret information marked "The Days of Chaos". Evidence points to the existence of an underground organization working towards a downfall of organized life as we know it. Plant evidence in houses of powerful NPCs, making it harder to get every adventure to get it, and, after 2 or 3 sessions, spring the trap; PCs are invited to a ball at which the Prince(ss) King (Queen) or Emperor (Empress) will attend!! Then they get to hear that the Oktoberfest is starting as of today! To make the joke a little less harsh, throw in a couple of magical items. (The evidence should be suspicious, but should also point to a big party, such as Octoberfest).