The Big Bang Theory turned out to be a major hit for CBS, lasting 12 seasons. The show featured several memorable moments, both of the laughter and emotional variety.

In the following, we'll take a look at memorable moments that turned out to be completely unscripted. Some were even more hilarious than the actual line itself - while others were extremely emotional for the cast.

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The particular moment we'll be taking a look at features Sheldon's final scene giving out his Nobel Prize speech. One line in particular caused a minor stumble for Jim Parsons. Let's take a look at what went down.

The Big Bang Theory Had Several Unscripted Scenes

It doesn't always have to be perfectly written for the cast. Now some sitcoms were quite strict when it came to sticking to what the script says, however, other sitcoms like Friends weren't afraid to try different things if something didn't land.

It was the same for The Big Bang Theory, as the cast created several memorable moments on their own. Perhaps the greatest scene of Sheldon shooting his roommate agreement papers in the air, and one paper landing on his head was completely improvised.

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In addition, Kevin Sussman revealed that he was able to get more cameos on the show due to an unscripted line which just came out, saying "I love you" to Penny in a low voice at the comic book store.

Despite the tremendous organic moment, Sussman did reveal that although going off the script was great, the writing was itself for the show always on point.

"The writers are so good that if a joke doesn't hit, the writers will converge on the spot and within three minutes have it rewritten—so it is funny," tells Sussman.

"The writers on The Big Bang Theory are probably the best in the business when it comes to on-the-spot writing. It's not a single camera show like The Office was," suggests Sussman. "Everything is very tightly-scored. There are four cameras all going at once, so everyone has to watch where their marks very closely. That doesn't leave any room for improvisation, really."

Inching towards the end of the series, things went off script for different reasons, as certain cast members could not contain their emotions.

The Cast Was Very Emotional Behind The Scenes During The Final Episode

The realization of the show coming to an end was not easy for a lot of the cast to digest. Kaley Cuoco was in shock by Parsons decision to leave, while Kunal Nayyar would also compare the end of the show to a very tough breakup.

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Getting through scenes was not easy, especially during the final episode. Cuoco had genuine tears during Sheldon's Nobel Prize speech. In addition, the table ready for the final episode was a task in itself to get through. Fans called it more emotional than the actual episode itself.

"This was more emotional than the actual ending 😥😥 Almost as emotional as the final episode of Friends," one fan stated on YouTube.

Although it was Parsons who decided to walk away - filming the final episode wasn't any easier. In fact, during his final speech, a certain line had him all choked up.

Jim Parsons Got Emotional During His 'Astronaut Howard Walowitz' Line

Arguably the most emotional part of the finale was Sheldon Cooper finally acknowledging all of his friends and thanking them. One tribute in particular had fans choked up and that was when Sheldon called Howard an Astronaut proudly. Given the battles they had on the show, especially given Howard's title, it was great to see Sheldon finally respect his close friend.

We can also tell the line meant a lot to Parsons, as he appeared to be choked up by it. The fans on YouTube would also discuss the subtle moment.

"No one ever noticed that Sheldon almost chokes up from emotion when he says "astronaut Howard Wallowitz."

"My eyes filled with tears when after all this time, Sheldon announces “Astronaut Howard Walowitz”. You have to be a BBT junkie to truly appreciate how beautiful that moment was."

"I broke down when he called Howard an Astronaut. Finally."

Yet another great moment true fans picked up on.

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