[Spoiler alert: The following article contains spoilers for upcoming episodes of "The Big Bang Theory."]
"The Big Bang Theory" is boldly going where no Sheldon has gone before!
After five long years of dating, a heart-wrenching break-up, and a yet-to-happen make-up, Sheldon Cooper and Amy Farrah Fowler are finally going to have sex this season.
ET caught up with "Big Bang's" It couple on the set of the landmark episode, and star Jim Parsons was quick to make jokes about Sheldon and Amy's highly-anticipated moment.
"Putting the 'bang' into the theory, I guess," the actor said causing his on-screen love interest, Mayim Bialik, to burst into laughter.
Clever puns aside, Parsons revealed that when he first discovered that Sheldon and Amy were finally going to embrace the intimate side of their relationship, he was stunned.
"I was very surprised," Parsons admitted. "But then I read it, and it seemed absolutely the right time."
In the episode, which airs Dec. 17, it's Amy's birthday and Sheldon gives her a present that she will never forget.
"I was kind of nervous when I first saw where it was going – that it was going to feel voyeuristic or kind of icky, but it’s very tender. It’s very sweet," explained Bialik, who has always been very protective of the characters' romance.
No surprise there! "The Big Bang Theory" might have started off as a quirky show featuring four brainiac scientists, but over the last nine years the CBS comedy has consistently surprised fans with some of the most romantic moments in TV history.
Parsons promises that Sheldon and Amy's first time will continue the series' tradition of balancing comedy with compassion. "It was fun to act. It wasn't hard to act," the four-time Emmy winner said.
"Or icky!" Bialik added
"Or icky," Parsons agreed. "Although, I never really thought it would be icky, I don't know why she says that. That may be a personal commentary."
To make this episode even more monumental, Bob Newhart is returning to reprise his role as the dearly departed Professor Proton.
Newhart, who previously won an Emmy for his guest role on the smash CBS comedy, will once again don his Obi-Wan Kenobi costume to act as Sheldon's spirit-form life mentor. He will appear multiple times throughout the episode in Sheldon's dreams and will help guide him to make a very important, life-changing decision.
"The Big Bang Theory" airs Thursdays on CBS.