Zac Efron unbuttoned his shirt and showed off his six-pack while filming Townies in LA yesterday. He got into the sports scenes with a few props including a basketball and baseball bat, but the real focus was on his tanned abs. Zac's been busy filming the college-set comedy since March, though his scenes haven't been all hard work. Zac kissed a costar during one rowdy take last month and has also sported a bathrobe and other costumes for the cameras. He did take a break from the on-set fun to promote a more serious project, At Any Price, at the Tribeca Film Festival after debuting the movie at the Venice Film Festival last year.