Is it possible for an actor to go through the motions even as he\'s going over the top? In Being Flynn, Robert De Niro does phoned-in scenery chewing. He gives a loud, ranting, shallowly aggressive performance as a \"colorful\" egomaniacal crank — a New York cabbie named Jonathan Flynn who spends his spare time scribbling away at an epic manuscript. He thinks he\'s one of the three greatest writers America has ever produced (the other two being Twain and Salinger). De Niro plays this outsider-artist deadbeat by pushing every line to the same level of empty, hectoring monotony. He never finds any poetry in Flynn\'s bellicose soul. He just makes you wish that the guy would shut up. Flynn is the estranged father of Nick (Paul Dano), an aspiring fiction writer who goes to work in a Boston homeless shelter, where he encounters his hitting-the-skids dad. Dano, the gifted young string bean from There Will Be Blood and Little Miss Sunshine, looks lankier — and moodier — in every role; with his saddened amoeba face, he\'s quite convincing as a dark-side-of-the-moon bohemian. But Being Flynn, which is based on Nick Flynn\'s memoir Another Bulls--- Night in Suck City, never convinces you its central relationship is authentic. It just seems like another bulls--- indie set in Suck City. C