Even haters can’t hate, hate, hate this video of Paul McCartney channeling his inner 15-year-old girl and jamming with Taylor Swift on “Shake It Off.” The ultimate bridge between generations went down at the “SNL” 40th anniversary after-party Sunday night — and Jimmy Fallon even joined them on stage too. Taylor returned the favor by rocking the Beatles, “Saw Her Standing There” — and she played a pretty strong rhythm guitar, while Paul played bass. If only Fallon had some drumsticks. It seems now that Taylor and Kanye have one more thing in common.