Celebrity·Posted on May 16, 2013Nick Offerman Sang Megan Mullally An Original Birthday Song On LenoWritten by Offerman himself, The Rainbow Song was dedicated to his wife. And also Nick's hair is really long.by Lauren YapalaterBuzzFeed StaffLinkFacebookPinterestTwitterMail View this video on YouTube youtube.com Tap to play GIF Tap to play GIF Tap to play GIF Tap to play GIF Tap to play GIF Tap to play GIF