Jonas Brothers were on the so-called Jonas Headquarters Mailroom to read the fan mails they've received in the past months when they decided to sing one of their fans, named Natalie, "Happy Birthday." Besides, they also took time answering fans' questions in addition to sing the songs their fans have penned for them.
They videotaped the moment and then posted the footage on YouTube. At the end of the video, the brothers pointed to a couple of boxes full of fan mails that they promised to read. In a post accompanying the video, Kevin Jonas, Joe Jonas, and Nick Jonas wrote, "Thank you guys so much! We love you all, and for those of you who've asked, here is the address to send all of your fan mail! We can't wait to read it!! Jonas Brothers C/O Ultrastar Entertainment 45 Main St. Brooklyn, NY 11201. Thanks again."
Here's the video of Jonas Brothers singing "Happy Birthday" for Natalie.