Many statistics for virtual world say that the number of teenagers who enjoy virtual worlds will be increased and about half of teens accessing the internet will enjoy the virtual worlds at the year of 2011. In order to satisfy their needs in such virtual world, we need to understand what they want to and reflect their real-life trends in the world. The paper deals with what the preferable social activities are in virtual world for teenagers. In order to do, we first analyze three major virtual worlds, , , and to characterize social activities for teens. Then we propose a characterization of effective social activities in virtual worlds for teens.