The Celebration Experimentation Season 9, Episode 17 -  Aired February 25, 2016

The Celebration Experimentation

After more than nine years together, the gang finally celebrates Sheldon's birthday, surprising him with a special guest, on the 200th episode of The Big Bang Theory.

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Guest Stars: Kevin Sussman as Stuart, Christine Baranski as Beverly Hofstadter, John Ross Bowie as Barry Kripke, Sara Gilbert as Leslie Winkle, Wil Wheaton as Himself, Adam West as Himself, Stephen Hawking as Himself

Writers: Chuck Lorre (Story), Eric Kaplan (Story), Jeremy Howe (Story), Steven Molaro (Teleplay), Steve Holland (Teleplay), Tara Hernandez (Teleplay)

Director: Mark Cendrowski

Viewers: 15.94 million Households Rating: 10.5/17 Adults 18-49 Rating: 3.8/14

Available on iTunes

Episode Notes

  • The title refers to Sheldon's decision to allow his friends to celebrate his birthday with a party.
  • This was the 200th episode of The Big Bang Theory.

Episode Quotes

Penny: So what's going on?
Sheldon: I don't know. I looked around the room, and I saw all the faces and the presents, and it it was just too much.
Penny: I get that. Hey, you want to just bring a few people in here? You know, Wil Wheaton in the bathtub, Batman on the toilet. It'll be like the weirdest Comic-Con ever.

Sheldon: I don't think I can go back out there.
Penny: That's fine. You know, I hate that your sister and her friends used to torture you. But what I hate even more is, if I was there, I would have tortured you, too.
Sheldon: Based on this pep talk, I'd say you're still doing it.
Penny: My point is, there was a time I never would've been friends with someone like you, and now you are one of my favorite people. So, if what you need is to spend your birthday in a bathroom, I'm happy to do it with you.
Sheldon: Well, everyone will think I'm weird.
Penny: Sweetie, you are weird. Everyone knows you're weird, but they're all still here because they care about you so much.

Leslie Winkle: Uh, in the past, I would've said something obnoxious, like, "Happy birthday, dumbass". But I'm not gonna do it. You and I have both grown a lot, and it's just so nice to see you all again. So happy birthday, Sheldon.
Sheldon: Oh. Oh, now, you know I hate change. Say it.
Leslie Winkle: Happy birthday, dumbass!

Amy: We've got someone who couldn't be here but really wanted to wish you a happy birthday.
Stephen Hawking: Hello, Sheldon.
Sheldon: (gasps) Professor Hawking.
Stephen Hawking: Happy birthday to you.
Sheldon: Thank you so much. I can't believe you're-
Stephen Hawking: Happy birthday to you.
Sheldon: Oh, you're singing. Well, I'm sorry.
Stephen Hawking: Happy birthday, dear Sheldon.
Leonard: Uh, Professor Hawking, if you just give us one second, we'll light the candles, and we can all sing together.
Stephen Hawking: I was crushing it, but all right.

Raj: You know, Adam West is my favorite Batman? Well, after Michael Keaton, Christian Bale and Batman from The Lego Movie.
Howard: Don't say that to him.
Raj: What? He beat out George Clooney. And that's something. Like, I love me some Clooney.
Leonard: Don't say that to anyone.

News Stories

Title Date Posted
917 'The Celebration Experimentation' Press Release February 18, 2016

CBS has issued the press release for the 200th episode of The Big Bang Theory, "The Celebration Experimentation", which airs next Thursday, February 25. The episode is packed with regular The Big Bang Theory guest stars with Christine Baranski, John Ross Bowie, Sara Gilbert and Wil Wheaton all appearing alongside special guest star Adam West.  Full story


As Sheldon and Amy walk down the stairs with Leonard and Penny, Amy raises a touchy subject with Sheldon. After Amy says she was hoping they could celebrate his upcoming birthday, Sheldon says he supposes that’s a discussion they could have. Amy thinks that’s great, until she turns around and sees Sheldon has disappeared.

As the group return to the apartment to look for Sheldon, he jumps out from behind the couch and scares them. Sheldon explains that is just one example of how birthdays can be terrible. When Amy asks why he doesn’t like to celebrate his birthday, Sheldon explains that nobody he liked would ever attend the joint parties he had with his twin sister. Sheldon says his sister’s friends would spend the whole day torturing him. Once, his sister made him believe Batman was coming to his party so he spent the whole day waiting by the door. Amy tells Sheldon that none of those things would happen to him now. After Sheldon questions why it’s so important to Amy that he celebrate his birthday, she explains it’s because he made her last birthday so memorable. After Penny tells Sheldon he has plenty of friends now who would love to come, Sheldon agrees that they can throw him a party.

At the comic book store, Howard asks Raj what he’s getting Sheldon for his birthday. After Leonard notices a Batman figurine in the store, he mentions the story Sheldon told about his sister tricking him into thinking Batman was coming to his party. After Leonard wonders if they could get Batman to actually show up, he talks to Stuart, who tried to get Adam West to do a signing in the store. Stuart agrees to give Leonard his contact information.

As they gather around the kitchen table in the apartment, the girls ask Sheldon about his preferences for the party: mylar balloons, no music, and chocolate cake with strawberry frosting.

When Leonard, Howard and Raj drive to Adam West’s house to pick him up, Raj talks about his favorite Batman actors. Back in the apartment, Penny thanks Stuart for helping with the cake as she rushes around preparing for the party. Meanwhile, as Leonard and the guys drive back with Adam West, he shares his opinions on the other Batman actors. Howard is surprised that Adam West puts himself above Christian Bale, but West insists people knew he was Batman without him having to say the phrase “I’m Batman.” After Howard asks if they can all agree they’re worried about Affleck, West wonders what an affleck is.

As Amy fixes Sheldon’s tie in Leonard and Penny’s living room, he wonders if there’s a reason he had to leave his apartment. Amy says they want him to see it for the first time all decorated. After Amy tells Sheldon he looks good in his suit, she wonders whether she will get to see him in his birthday suit later. A puzzled Sheldon says this is his birthday suit.

As Leonard and Penny chat with Beverly in the apartment, he is surprised Beverly came all this way for Sheldon’s birthday. Beverly says she was happy to after Sheldon came to her 60th. Leonard is irked that she had a birthday party without him, but Penny points out they didn’t invite her to their wedding in Vegas. Meanwhile, Sheldon is sitting anxiously on Penny’s couch when Amy’s phone beeps. After saying Penny said everyone is there, Amy asks if he’s ready. Sheldon says he is.

As they walk across to the apartment, Sheldon stops suddenly and admits he feels a little light-headed. Amy asks if he needs a minute, but he says he thinks he can do this. As Sheldon enters the room, the guests cheer and shout “Happy Birthday”. After Leonard calls for a speech, Sheldon thanks everybody for coming. He is surprised to see Beverly, Wil Wheaton, and Adam West for some reason. Leonard explains that Batman finally came to his party. As Sheldon tells them this is all so thoughtful, his heartbeat quickens as he looks around the room at all the faces. Sheldon excuses himself and runs off to the bathroom.

After Leonard and Amy argue over who knows Sheldon the best and should go talk to him, Penny has enough and takes it upon herself to go see Sheldon. After Sheldon lets her in to the bathroom, Penny asks what’s going on. Sheldon says looking around the room and seeing all the faces and presents was too much. When Sheldon apologizes for ruining the party she worked hard to put together, Penny insists he’s not ruining it. After Sheldon tells her he doesn’t think he can go back out there, Penny says it’s fine. When she sits down with him on the bathtub, Penny tells Sheldon that she hates that his sister and her friends used to torture him. What she hates even more is that she knows she would have tortured him too if she was there. Penny admits there was a time she never would have been friends with someone like Sheldon, but now he is one of her favorite people. Penny tells him that if he needs to spend his birthday in a bathroom, she’s happy to do it with him. After Sheldon worries everyone will think he’s weird, Penny tells him he is weird and everyone knows it, but all came because they care about him so much.

Back in the living room, Leslie Winkle catches up with Leonard. When he tells her so much has changed since they last saw each other, Leslie isn’t sure. After Leonard mentions he and Penny got married, Leslie congratulates him, admitting she thought he would be living with Sheldon forever. Unsure what to say, Leonard tells her not to be a stranger.

Penny comes out of the bathroom to tell the crowd that Sheldon is going to return, but he’s a little embarrassed so they should all be extra nice. When Sheldon appears, he apologizes for his behavior and tells everyone to enjoy themselves. After Amy proposes a toast to Sheldon, she explains she feels like she got the greatest gift the day he was born. Enjoying the fun, Sheldon asks for other people to say wonderful things about him.

The toasts continue coming from Howard, Wil Wheaton, Beverly, Raj, Leslie Winkle, Adam West, Bernadette and Leonard. When it’s Stuart’s chance at last, he gets cut off by Amy who is holding a laptop with a video call with Stephen Hawking. When Professor Hawking starts singing “Happy Birthday”, Leonard asks for a second to light the candles so they can all sing together.

After Stephen Hawking leads a long-distance round of “Happy Birthday”, Sheldon blows out the candles on his cake. Adam West asks which one of them is taking him home.