Judd Apatow has fulfilled his promise to "shake Americans from their squeamishness about male anatomy in movies" by featuring Forgetting Sarah Marshall star Jason Segel completely nude in the movie's pivotal break-up scene. And as the LAT pointed out yesterday, Segel's manhood provides the film's "most captivating screen presence" (sorry, Kristen Bell). But Apatow and his cool comedy clique aren't the first ones to boldly focus their cinematic lens on male actors' full frontal displays. We took a look back on Segel's predecessors to showcase other (pun intended) ballsy big-screen cameos by the likes of Bruce Willis and Ewan McGregor after the jump. Just a warning, this is NSFW.