'The Big Bang Theory' Cast on Series Finale, First Impressions and Who Hooked Up in Their Dressing Room

It was "Big Bang Theory" all night long on CBS -- if you thing "S.W.A.T." stands for "Sheldon Wins a Thing" -- and the series finale celebrations continued into "The Late Show," where the cast got the chance to ask each other some hard-hitting questions.

One thing was clear throughout their segments with Stephen Colbert, and that is just how close this group has gotten over the past twelve years. And yet, this will likely be one of the last times Jim Parsons, Johnny Galecki, Kaley Cuoco, Mayim Bialik, Kunal Nayyar, Simon Helberg and Melissa Rauch are all together.

As Colbert pointed out, it's incredibly rare to do what they have done in creating a show that transcended television and became a cultural phenomenon. It is the latest sitcom to have achieved this, and with the way television viewership continues to evolved, it may well be the last.

One of the scariest things about being on a long-running show that is wildly popular is sticking the landing. Just ask red-hot series like "Lost," "Seinfeld" and (so far) "Game of Thrones" what it's like when people are disappointed in your ending?

"We were talking to the writers a lot as we were getting ready and one of them was like, we're nervous," Jim Parsons told Colbert. "And I was like, well you can't get it wrong. I mean, it's yours. You've been writing it all this time."

When that didn't work to soothe the writer's frazzled nerves, Parsons told him, "Well look at it this way. You can't get it right. it's a series finale. Someone's gonna hate it."

At the same time, he felt confident that this series finale would not be nearly as divisive as so many others have been. "We'll find out tomorrow," he joked.

Jim Parsons admitted to something big here, but only after Kunal Nayyar cracked the joke that his first impression of his cast-mates was that "everyone was very good looking."

"Wait a minute? Is that your real answer?" Parsons asked him.

He then revealed a little how the sausage is made, talking about the pre-interview he did with Colbert's team on this question. "I said so-and-so is really funny, so-and-so I just thought was whatever.,But Kunal I thought was the most handsome man," Parsons said. "I have a thing for brown hair and brown eyes and he really checked off my boxes."

Johnny Galecki said that the entire cast thought Kaley Cuoco was "too cool for school," because she always took off after rehearsals rather than hang out and party with them. Cuoco, who said she was 21 when the show started, turned it around on them and said she had no idea.

"We started talking about it and he was like why don't you ever go out with us and I was like, you guys go out?" Cuoco said. "And he goes, we thought you were too cool. I'm like, you never invited me!"

After Mayim Bialik admitted to geeking out over Bob Newhart -- admitting "I cannot control myself" -- Galecki recalled the time he may have freaked out Judd Hirsch when he saw him out in public.

"I ran up to him and I said, I'm a massive fan of 'Taxi' and your role on that and I kind of tried to base the purpose of my character on the purpose of your character," Galecki said. "And then I said, You wanna play my dad? Do you want to come on and play my dad?"

It was then that he took stock of what was happening and "realized he might not have any idea what show I'm talking about, or that I'm an actor even."

Finally, it was time for Colbert to ask the cast questions they themselves had anonymous provided. One question that seemed to be on several people's minds once Colbert asked it was when Cuoco learned her lines, "because apparently in 12 years, no one saw you look at scripts."

"I don't look at the scripts," Cuoco admitted. "They do make fun of me for that. I usually have a magazine in my hands instead of the script."

"Make fun of you?" Parsons asked incredulously. "She doesn't look at it, she says it word perfect." But the real magic is that she kept her secrets and didn't say how she performed this feat. Photographic memory? Written around the set where only she can see them? In tiny print on her hands?

Another question they apparently couldn't bring themselves to ask one another until it was anonymous was whether or not any of them had hooked up in their dressing rooms. After a pause, Galecki raised his hand.

"And that did not include me," Cuoco joked, with her hand firmly down. Galecki and Cuoco famously dated earlier in the show's run.

When nobody else raised their hands, Simon Helberg quipped, "We all used Johnny's dressing room."

Finally, Colbert asked which character from the show would they have wanted to play if they couldn't play their own. Some of the answers were interesting to consider, but then one of them said Cinnamon the dog. Okay, that would be interesting to consider, too.

The cast was clearly having a good time, and captured the moment themselves in a selfie taken by Jim Parsons, as shown above. Cuoco posted the adorable picture taken, which you can see below, as part of a series of remembrances and behind-the-scenes moments from throughout the show's final weeks on her Instagram page.

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