“There’s Something About Mary” helped launch the modern era of bro-humor comedies (“Hot Tub Time Machine,” “The Hangover,” Seth Rogen’s entire career). In 1998, mining humor from the mentally retarded, catching your scrotum in your zipper and mistaking semen for hair gel was somewhat taboo. Now you see all that and more in the trailer for a Will Farrell flick. But “Mary” deserves credit for shock-humor originality. Cameron Diaz nails her part. And admit it, some scenes are a hoot (franks and beans; the serial killer sequence; Ben Stiller mispronouncing Brett Favre’s name). Plus, the minstrel/soundtrack is prominent and excellent.