Although Mr. Murphy breaks me up, he just can’t get very far from crudity and profanity. “The Nutty Professor: 2” is rated PG-13 for one crude sexual comment after another. When humor isn’t extracted from broad sexual innuendo, Mr. Murphy turns to gross-out visuals, jokes about old age and the always reliable flatulence sound effect. Intestinal gas gags are repeated not once, not twice, but over and over. Unfortunately, the newest generation must believe that all comedy is based on bodily functions. But all you have to do to prove that theory wrong is to rent the original “Nutty Professor” with Jerry Lewis. Or if you want three hours of comedy with nary an objectionable word or action, try renting Blake Edwards salute to melodramas, “The Great Race.”