Two teenage pals turn into vampires and prove too cool for school in this rousing adaptation of Darren Shan’s popular young-adult novels. Hell-raising Josh Hutcherson ropes amiable buddy Chris Massoglia into attending a freak show, and they meet a wisecracking bloodsucker (John C. Reilly, terrific) who pulls them into a war between the vampires and their ruthless cousins, the vampaneze. Mixing horror and comedy while minimizing the gore, writer-director Paul Weitz (About a Boy) serves up a witty adventure fantasy with a tasty dollop of schadenfreude. Ken Watanabe, Patrick Fugit, Salma Hayek, and Willem Dafoe costar. PG-13, 109 min.