Video: 'The Big Bang Theory' Flashmob

Stars of “The Big Bang Theory” know how to have  good time, and lately, they made sure they got their audience involved in the fun during a taping of a live show.

As they were filming, the cast seemed surprised when Carly Rae Jepson’s voice began to sing over them.

The show’s stars, Kunal Nayyar, Simon Helberg, Johnny Galecki, Mayim Bialk, Melissa Rauch, Jim Parsons, and Kaley Cuoco, as well as some cast and crew, then jumped into a coordinated “Call Me Maybe” flash mob, surprising and delighting their audience.

At the end, Parsons, as his character Stanley, told the crowd his signature, “Bazinga!”

Star Kaley Cuoco tweeted her joy about the moment, teasing audiences Wednesday before the Thursday reveal.

“Ok it's here! The moment I've been waiting for! I finally get to share the surprise!! the BIG BANG THEORY FLASH MOB!”

She posted a link to the video, and later, tweeted again, “Who enjoyed the flash mob?! FYI that was only a tiny piece of it!! Trying to get you the rest of it!!!! Aaaghhhh!!”

Cuoco was reportedly the “mastermind” behind the plan, and coordinated the dance with the help her sister.

Chuck Lorre, the show’s creator, was apparently not in on the joke. He seemed just as surprised as audience members when the cast starting grooving.

“What is going on?” Cuoco yells over the music, as cast members begin to dance.

Within a moment, she and the rest of the cast leap up from their places and jam to the strangely infectious song.