For a while Friday, when it looked like someone had made off with the Wally the Green Monster get-up, a few funny people were imagining the next great Boston-based caper on the big screen. “We need a narrator . . . ‘From director Ben Affleck,’ ” tweeted Grantland columnist Bill Simmons . Affleck, director of “Gone Baby Gone” and “The Town,” isn’t on Twitter much, but he saw Simmons’s tweet, and promptly replied: “Opening scene for The Town 2?” That’s a movie we’d pay to see.