Taylor Swift has made a highly lucrative career out of playing an awkward nerd, so it might not seem impressive when she goes full Urkel in a “Tonight Show” guest appearance. But it is. Swift joined Jimmy Fallon for an episode of “Ew!” in which she got to discuss her Band-Aid collection, “pegacorns,” and “The League of Extraordinary Gentlemen.” Good on her: It's a cute performance and the hair is perfect.