Kaley Cuoco was the perfect fit for Penny on The Big Bang Theory. However, Cuoco and her team contemplated turning down the offer, given that they were into the Katie character instead. Cuoco and her team also feared that Penny was more of a background player. Obviously, that was not the cast and thankfully, Cuoco took the offer and it changed her career, becoming a memorable part of The Big Bang Theory for 12 seasons.

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Throughout her 12 seasons, Kaley Cuoco had more than a few memorable moments. In following, we're going to take a look back her favorite moment from season 4, alongside an extra. It was a nervous moment for Gabriel Tsai, who had to go against what he believed in. Ultimately, it was all worth it as it made for a hilarious scene and an episode fans adored.

In addition, we're going to take a closer look at what it was like being an extra on The Big Bang Theory. Finally, we'll reveal other moments Kaley Cuoco wasn't as pleased with, particularly a certain storyline.

Working As An Extra On The Big Bang Theory Included Lengthy 10-Hour Days

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A photo of Kaley Cuoco eating in a red shirt behind the scenes on The Big Bang Theory.
via YouTube 

Getting cast as an extra on The Big Bang Theory can be a dream come true for any super-fan. That was the case for Jenny Chen, who spoke about her memorable experience alongside Medium.

What Chen didn't realize is how lengthy the process was for her work as an extra. Although Chen loved her minute of it, her day lasted 10-hours.

She recalls, "We wrapped at around 5:30pm, a 10 hour day. Overall this was an unbelievable experience for me, not only because I was able to be on set with the cast, but also because the entire day was full of twists and turns that I hadn’t expected."

"I didn’t end up using any of the clothes I brought and ended up wearing a costume with shoes that hurt my feet, but I was delighted by the changes nonetheless."

RELATED - Jim Parsons Worried About His On-Screen Relationship With Mayim Bialik If The Big Bang Theory Decided To Continue Without Him

Chen would even recall Parsons' arguing about his lines with the writers, and how they didn't necessarily make sense for the scene. Although Chen had a positive experience, another extra was in a very stressful situation alongside Kaley Cuoco during season 4.

Kaley Cuoco Had To Convince Extra Gabriel Tsai To Get 'Handsy' During Their Dancing Scene In Season 4

Kaley Cuoco big bang
A photo of Kaley Cuoco dancing in purple on The Big Bang Theory.
via IMDb

Back in 2011 at the San Diego Comic-Con, Kaley Cuoco revealed that her favorite scene from season 4 came alongside an extra by the name of Gabriel Tsai. In the episode, The Agreement Dissection, Tsai was very unsure about what he had to do. So much so, that it took convincing from Kaley Cuoco herself.

Cuoco recalls, "I guess it was where I had a lovely man have to grab my ass in an episode when we were dancing. And he was a little older man, and he was so nervous. And it was so against everything he believed in, and I was like, 'Honey, just grab it. Just do it.' And he closed his eyes and just went for it."

RELATED - Jim Parsons Didn't Have The Easiest Time Remembering His Lines, According To A Big Bang Theory Extra

In truth, it was all worth it, and it made for a very memorable episode as Sheldon decided to join the women during their girls night. Without a doubt, it was a moment the extra won't ever forget and clearly, it also had an impact on Cuoco who called it the most memorable moment from the fourth season.

Kaley Cuoco Wasn't A Fan Of Every Scene On The Big Bang Theory, Especially The Serial Ape-ist Storyline

Kaley Cuoco and Johnny Galecki
A photo of Kaley Cuoco and Johnny Galecki talking to the audience behind the scenes on The Big Bang Theory.
via CBS

Kaley Cuoco wasn't always onboard with everything that took place during her time on The Big Bang Theory. Looking back at some of her worst memories, the serial ape-ist storyline always comes to mind, especially given the prep that had to take place behind the scenes.

Cuoco recalls, “The worst experience was filming Serial Apeist and getting covered in hair from head to toe,” she says. “I was like, ‘Really, you guys? This is what’s happening?’ And Chuck just thought it was so funny. He loved it. I never understood why,” she wrote.

However, Lorre would agree that the scene was regrettable.

“Doing a show within a show — writing the ‘bad’ scenes that she’s in, in an otherwise good show — was not our finest moment. The goal was legitimate, which was to put her in a bad move and see her struggling to make something work,” he admitted.

Lorre and company had other regrets along the way for Penny's character, which included the awkward storyline with Raj, when the two were caught in bed together. Following that finale, the writers spent their time off trying to fix that mistake and confirm that nothing had ever happened.