Unsurprising news: Captain Underpants is a silly movie. Surprising news: it’s also not bad. Based on Dav Pilkey’s popular children’s novels of the same name and directed by David Soren (Turbo), DreamWorks’ Captain Underpants pretty much comes as advertised: it’s about a big, dumb guy in Y-fronts and a cape. Like the book series, the Underpants movie centres on two fourth-grade best friends and neighbours, George Beard (Kevin Hart) and Harold Hutchkins (Silicon Valley’s Thomas Middleditch), and their efforts to inject a bit of life into their grim middle school existence, under the authoritarian grip of principal Mr. Krupp (Ed…