MIAMI (CBSMiami/ET) – Kaley Cuoco’s sister, Briana Cuoco, is cluing in Big Bang Theory fans on which of the cast has the fanciest footwork!

ET’s Keltie Knight caught up with the actress in L.A. where she discussed choreographing all three of the flash mobs which went down on the show’s set over the years, and it turns out some of the stars are born dancers.

“You know who kinda kills? It is Mayim [Bialik],” she reveals. “Mayim slays it! And Kunal [Nayyar].”

She also shared that at least one actor embraced their character’s nerdy habits in order to get the routine down.

“I will say that Jim [Parsons] had flash cards,” she says. “He would write down all the choreography on flash cards…. I swear! But then he felt a little FOMO and needed to get into the next ones.”

The Big Bang Theory’s hour-long finale airs Thursday, May 16 at 8 p.m. on CBS.