As displayed in the picture above, the international campaign slogans "Do drugs control your life?" and "Your life. Your community. No place for drugs" will be featured in Rappelz for the event. Virtual gifts will also be given away, presumably educational in some form. Game Power 7 stated that using their virtual world to promote good values in the community is part of the company's strategy, so future events of this kind might find their way into the game.
To find out more about the International Day Against Drug Abuse and Illicit Trafficking, the best place to start is the UN's official page, which also features links to some nation-specific pages.