EXCLUSIVE: Kunal Nayyar Explains How Entire 'Big Bang Theory' Cast Got Sick, Dishes on Kaley Cuoco's 'Yoga Thu

The mystery behind The Big Bang Theory cast's big bug has finally been revealed!

Just two days after Kaley Cuoco announced over Instagram that "everyone at work is sick," ET chatted with her co-star, Kunal Nayyar, at the UCLA Institute of the Environment and Sustainability Gala on Thursday in Los Angeles, where he dished on how the cast of the popular CBS sitcom all fell ill.

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"Literally everyone is sick!" the 34-year-old British-Indian actor confirmed. "We were rehearsing and we were doing scenes, and we were all wearing surgeon masks, doctor masks, because everyone was sick."

It was apparently a domino effect on set, as Nayyar and his co-stars started getting sick one by one.

"It started, I think, Mayim [Bialik] had it first, and then Kaley, also -- everyone's got kids now," he explained. "Simon [Helberg]'s got kids. It's just -- everyone's getting sick all the time. I think Mayim gets it from her kids, or Simon gets it from his. And they come to work and we're all hugging -- we're all very close. It's funny. We were literally doing scenes [and we'd] take off the mask like this, and put it back on."

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According to Nayyar, it got so bad on set that they had to resort to calling a professional for help.

"We had to bring the doctor to set like three times," he told ET. "We were all taking like Theraflu, or whatever it is."

Yikes!

Nayyar also said that due to their intense shooting schedule, the cast tries their best to eat healthy on set. So, who's the most health-conscious?

"Me! I never get sick," he exclaimed. "It's because I'm from India, so I've seen every kind of bacteria you can imagine."

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Yoga lover Cuoco also encourages her co-stars to stay healthy, by leading on-set yoga sessions.

"We have yoga Thursdays," Nayyar revealed. "So, at lunch, she teaches us all yoga on Thursdays."

All health aside, Nayyar said that on a more serious note, he's looking forward for what's to come next on The Big Bang Theory -- including having a baby on set!

"When I first read the script, I almost fell out of my chair," he joked, referring to the story line of Howard and Bernadette (played by Helberg and Melissa Rauch, respectively), who are expecting their first child together in the series. "The writers have never led us astray. They have an incredible and impeccable plan for next season, so, we'll see what happens."

"Next year is season 10, and I hope it's not our last," he continued. "I hope we keep going."

WATCH: Kaley Cuoco Reveals the Whole 'Big Bang Theory' Cast Is Sick

Kaley Cuoco Reveals the 'Big Bang Theory' Cast Is Sick -- See the Pic!

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