The Big Bang Theory: 8 Moments That Were Completely Unscripted
3. The Theme Song
The show's iconic theme song was written and performed by Canadian rock outfit Barenaked Ladies, with the tune detailing the origins of the universe in supremely catchy and unforgettable fashion.
The group's frontman Ed Robertson was originally approached to write the song after the show's creators, Chuck Lorre and Bill Prady, attended one of their concerts in Los Angeles.
In what turned out to be a most fortuitous coincidence for everyone involved, Robertson had just finished reading British scientist Simon Singh's book "Big Bang," and decided to launch into a totally improvised freestyle rap about the origins of the universe at the concert.
This prompted Lorre and Prady to contact Robertson and get him to write the theme for the show in earnest, effectively adapting that off-the-cuff rap into an actual song.
Robertson agreed, but only if he was the only person they'd asked to make a song for the show, as he'd previously been asked to write songs for TV and movies only for the producers to pick an alternate instead.
While it's probably fair to assume that Robertson revised his original rap into something more refined, the bones of it were absolutely improvised during that concert. Better yet, Robertson apparently came up with the final version in the shower just 20 minutes before he had to present it to the duo on a conference call.
It surely turned out to be the group's shrewdest decision to date, earning them much greater visibility and a whole new fanbase in the process.