“The Big Bang Theory” cast had quite a bit of fun recently on the set of their live episode taping; without the director or producers knowing, the group choreographed a flash-mob dance routine to Carly Rae Jepsen’s “Call Me Maybe” (with help from Kaley Cuoco’s sister) and broke it out while the cameras were running, much to the surprise and delight of the studio audience.

“Sheldon” stole the spotlight, however, with a well-timed “Bazinga!”