After attending the Nickelodeon 2009 Kids’ Choice Awards, the Jonas Brothers visited Perez Hilton’s 31st birthday party at The Viper Room in West Hollywood on Saturday night (March 28), negotiating their way through the paparazzi and signing a few autographs for resellers. While inside, the sibling pop trio led the crowd in ‘Happy Birthday’, captured on video by Katy Perry’s BFF Markus Molinari. Watch the footage below.