To celebrate the syndication launch of the CBS hit The Big Bang Theory, Canadian alt-rock band Barenaked Ladies crashed the set of the nerdtastic show to perform the insanely catchy theme song. The band plays the song smack dab in the middle of Leonard and Sheldon’s spacious apartment. The tune was conceived back in 2007 when BBT co-creators Chuck Lorre and Bill Prady asked Barenaked Ladies frontman Ed Robertson to pen a theme song for the series as a “sort of history of everything … in about 32 seconds.” The music video features never-before-seen behind-the-scenes footage of the show’s table read, rehearsals and episode taping, and don’t miss co-creator Chuck Lorre handling a guitar. Don’t be shy, sing along! Our whole universe was in a hot dense state…

Oh, and if you’re interested, The Big Bang Theory debuts in syndication September 18, simultaneously on TBS, the Fox Television Stations and broadcast stations across the country, and will air five nights a week. Season five premieres Thursday, September 22 at 8PM on CBS.