Ed Robertson of Barenaked Ladies Ed Robertson of Barenaked Ladies

One of the highlights of Comic-Con 2010 was the surprise appearance of the quirky Canadian pop-rock band Barenaked Ladies at The Big Bang Theory panel to sing their catchy theme song to the hit CBS sitcom. (Sample lyric: "Religion or astronomy, Descartes or Deuteronomy, it all started with the big bang.") It was an exhilarating moment for the crowd — and the cast. "To hear thousands of fans screaming and singing along with them was truly moving for me," says Simon Helberg, aka Howard Wolowitz. "Nothing to make a man question his masculinity like crying during an accordion solo."

For those who weren't lucky enough to get into Ballroom 20 of the San Diego Convention Center last year for the impromptu show, here's some good news: The band has recorded a music video for the song, and we've got it right here. "We visited the set and we were around for a couple of days while they shot an episode," Ladies front man Ed Robertson says. "So on top of our performance, you really get a sense of the development and shooting of an episode of the show and what that feels like. It was a lot of fun to be around. They really have a good time making that show." Series stars Johnny Galecki, Jim Parsons, Kaley Cuoco, Kunal Nayyar and Helberg all appear in the video.

Robertson counts himself as one of the Emmy-nominated show's biggest fans. "I like how the show really champions intelligence," he says. "I'm a nerd myself. I read science and math books." In fact, he had just finished a book called Big Bang: The Origin of the Universe when series creators Chuck Lorre and Bill Prady approached him to write the theme song. "It was incredible timing. I thought I was being Punk'd or on Candid Camera."

The music video and a special featurette, complete with interviews with the band, will be available on The Big Bang Theory: The Complete Fourth Season Blu-ray and DVD (on sale Sept. 13).