How often does a comedy come along that you don’t know exactly where it’s going? Rarely, and that’s why this one starring Zach Galifianakis, Bradley Cooper, Ed Helms and Justin Bartha as four shlubs and a bachelor party gone wrong in Vegas is such a revelation. As they find out what happened during their one-night blackout (clues include Mike Tyson’s tiger and someone’s baby in their hotel room, a missing tooth, a stolen police car…) in one ridiculous circumstance after another, the real mystery deepens: what happened to the groom-to-be?