The hilarious misadventures of the "Sket Dan"; a trio of high-schoolers who help out people as part of their club activity. Himeko, the violent "yankee"-girl with a soft spot for cute things. Switch, the brainy otaku who only talks via a computerized speech-application. And Bossun, the atypical leader of this looney bunch.
You can find the chapters of this hilarious series here: http://www.mangafox.com/manga/sket_dance/