Paul McCartney took some time out of his concert at Barclays Center on Tuesday night (Sept. 19) to call out Fallon and say happy birthday, and then, of course, sing "Birthday" to the 43-year-old Tonight Show host, who was in the audience not believing that everything was real. "Wait a minute, who's this guy?" McCartney says from the stage, looking out to spot Fallon. "Hey, wait a minute, is that Jimmy, Jimmy Fallon?... Happy birthday Jim! Okay Jim, this is especially for you and the other people who who've got a birthday." Watch the videos below: https://twitter.com/barclayscenter/status/910353507567489025 https://youtu.be/d7C0uEnWxb4