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"The Bitcoin Entanglement"[1] is the ninth episode of the eleventh season of the American sitcom The Big Bang Theory. The episode aired on Thursday, November 30, 2017.


Sheldon tries to teach the guys a lesson after they cut him out of a potentially valuable Bitcoin investment. Also, a seven-year-old video reveals a secret about Leonard and Penny's relationship.[2]

Extended Plot[]

The guys enter the comic book store as Raj is wondering why they are making four new "Avatar" movies. Stuart announces a special where if someone buys something, they will still have a comic book store to visit. Sheldon starts a conversation on Bitcoins that are now worth $5,000 apiece. Seven years ago the guys minus Sheldon mined some Bitcoins using Howard's old laptop. Stuart insists that he remembered mining them with him so that he can be in the windfall.

Flashback: Entering the old comic book store seven years ago, the guys are talking about the new "Avatar" movie and that Leonard and Penny had just started dating again. Howard is talking to his mother while Sheldon wonders why Leonard was there and not having coitus with Penny. Leonard is worried if Penny is going to stay with him or breakup again. Stuart approaches and Sheldon asks him if he accepts the new virtual coinage Bitcoins. He describes how one has to solve complex mathematical problems to earn the coinage. The guys are totally into spending a whole night trying to accumulate the Bitcoins. Stuart doesn't join it because it is too rich for his blood and Sheldon doesn't because he is worried about the tax implications.


I know too.

Present, Sheldon had been telling the story. Raj finishes that Sheldon warned them that someday they would regret it though the guys didn't because they thought they were rich.

In Halley's room, Howard gets out his old laptop from 2010. Raj wants to buy a tiger, while Howard might not tell his wife. Bernadette can hear him over the baby monitor, to which he responds he may put it in Halley's college fund. Howard doesn't find the Bitcoins, but there is a lot of Asian porn on it. There's a private folder on the laptop, though Bernadette checked that part and none of its in there.

Flashback: Leonard, Howard and Raj are doing manly things by "mining" on the internet in Howard's old bedroom. His mom wants to make sure that they aren't roughhousing. Scientists don't roughhouse. "Excuse me, Mr. Grown-up," exclaims Debbie Wolowitz. Then the laptop crashes due to all the Asian Leonard offers to finish using his laptop, but they don't get started until after they have the cookies Mrs. Wolowitz baked.


Checking out his laptop.

Back in Halley's room, they realize that they have to check Leonard's old laptop. Bernie yells at them asking where they are going sounding like her late mother-in-law. Answer, off to find Leonard's computer. She sends them on their way so they can get the money.

Penny, Sheldon and Amy are in apartment 4A discussing wedding plans. The wedding on a cliff overlooking the sea is off due to Sheldon's objections to the beach, cliff and the outdoors. The important thing about a wedding is to do it in front of your friends and family and to never move back into her apartment according to Penny. The guys storm in looking for Leonard's old computer. Sheldon then relates what happened to it.

Flashback: Penny and Bernadette are working at the Cheesecake Factory and Bernadette will not wait on Penny's table, where there sits an annoying person. There sits pre-Sheldon Amy on a date. She has Penny take their picture and then tells her date to leave. She can now prove to her mother that she was on a date. She also asks for Penny's name in case she needs a witness. "Bernadette". Checking on the guys, Raj is still not able to talk to women. Penny lost an audition because she didn't get the email since her computer is broken. Leonard gives her his computer since he is getting a new one.

Back in 4A, Penny remembers that what Leonard did and still thinks that that is so sweet. Unfortunately she gave it to Zack. Leonard doesn't think that it was thoughtful to give away his gift; however, she and Penny were broken up at the time. Penny calls Zack to get it as the group goes through a history of all their couple breakups. They even named Leonard and Penny's.

Flashback: Penny and Bernadette are at the Cheesecake Factory discussing her breakup with Howard, he had been doing all this weird stuff online. Penny was broken up with Leonard and runs off with Zack.

As the Hofstadters' leave Apartment 4A, Penny can't believe that Leonard is mad about her giving away his laptop. He claims not to be mad, but Penny can see it in his eyebrows. Leonard then explains that Penny giving away his laptop and going out with Zack were clear cut signs that he cared more about their relationship than she did, which she denies.


What did you do, Sheldon?

At Zack's apartment, Zack is glad to see them and that they should do this more often. Pick up laptops? Totally! Zack kept the laptop as he understands the value and appreciation of a gift from someone else (Leonard is satisfied that he knows this). Leonard is still upset that she went back to Zack so quickly. Zack insists that she kept talking about Leonard and was hooked on him because they were so much alike. They were both...people. Zack then adds that he knows how much she was hooked on him because of the video she left on his laptop.

Flashback: Drunk Penny is on Leonard's laptop in her old place. Penny wants to leave Leonard a message to give him an explanation on their breakup. Sheldon knocks on the door and Penny says to go away since she is making a video. Sheldon wants to know why she went out with him in the first place. Because he is great and if she kept going out they would have eventually got married, that was scary and she wasn't ready for that. Also she would have to learn to spell Hofstadter. She asks Sheldon what to do. He replies that she should pass out face down so that she won't choke on her vomit. Penny then does just that. She lies there for two more hours and then falls off the chair.


Passed out on her lap top - 2010.

At Zack's apartment, Leonard is touched that she loved him so much. Penny adds that she did marry him, with Leonard adding that she did it out of love and not out of pity like everyone else said at their wedding toast. Zack and Leonard proceed to watch Penny fall off the chair in the video several times.

The couple return to their apartment with the computer. Raj is not planning on paying his father back for all the money he gave him. On the computer, Howard can't find their coinage. Penny is sure that Zack didn't steal it since he's not smart enough to do so. Sheldon asks them where it might be. Amy tells him to confess. Sheldon downloaded it and shifted to Leonard's Batman flash drive. He wanted to see him sweat and waited seven years to see it, but assures him that he has had the Bitcoin all along; however, Leonard tells him that he lost that key chain years ago. A now embarrassed Sheldon considers that unfortunate, but he feels everybody learned a lesson today. Amy asks him what the lesson is and Sheldon shakes his head as he understandably can no longer remember.

Flashback: In the old comic book store four years ago, Stuart is cleaning up and finds a Batman flash drive (presumably Leonard's). He plans to erase it and sell it.



  • Title Reference: Refers to the mess the guys have in trying to find their stash of Bitcoins.
  • Taping date: October 31, 2017
  • This episode was watched by 13.84 million people with a rating of 2.5 (adults 18–49).
  • Total viewers including DVR users 18.54 million.
  • This episode aired in Canada on November 30, 2017.
  • Chuck Lorre's vanity card [1]


  • Nicholas Graff at Science - Coming off a little break, I'm pleased to say 'The Big Bang Theory' had another upswing this week, with a format breaking episode that not only reminded us of the golden age of the show, but also had its own share of great moments and laughs. The flashback heavy episode, which frankly I'm surprised they have not done before, was a great bit of nostalgia harkening back to the show as it was 7 years ago, and giving us the best of the old days while also delivering some genuinely funny jokes in the present. [2]
  • IMDb user reviews [3]


  • Zack returns in this episode, his most recent episode being "The Cognition Regeneration".
  • Zack returns for the second time for a flashback scene.
  • Bitcoin is a type of digital currency in which encryption techniques are used to regulate the generation of units of currency and verify the transfer of funds, operating independently of a central bank. At the time of airing, Bitcoin was worth almost US$10,000 each, double the amount mentioned in the episode.
  • This episode includes many flashbacks to 2010 and 2013, where the characters dress and act as they did in the earlier seasons; Raj cannot talk to women, Howard is living with his mother who is alive, Penny lives in Apartment 4B, Amy hasn't met Sheldon and has a total lack of social skills, Bernadette is broken up with Howard, etc. The flashbacks appear to take place during the events of Season 3, specifically after Leonard and Penny and Howard and Bernadette break up and before the season finale. Also, the old sets of the first comic book store, the Cheesecake Factory and bar and what was once Howard's Bedroom are seen.
  • This episode revealed that Amy and Penny met indirectly without even realizing it.
  • Voice archives of Mrs. Wolowitz are used for her "appearances" in the flashbacks, being the first time that her voice is heard since Season 8's "The Prom Equivalency", which is also the season that her actress and character passed away.
  • Present-day Bernadette does not appear, though her voice is heard in this episode through Halley's baby monitor. She only appears in flashbacks.
  • Bernadette stands behind the Cheesecake Factory bar, likely to hide Melissa Rauch's growing belly, as at the time of filming she was expecting her first child. This may be an oblique nod to how the same was done to conceal and accommodate Kaley Cuoco's leg, in a cast following a horse-riding mishap, in several season 4 episodes.
  • This episode was advertised to include a "major revelation" about Leonard and Penny's relationship through the seven year old video left by a drunk Penny. She apologized to Leonard for breaking up with him in "The Wheaton Recurrence" because she loved him and was freaked out that someday they might get married and that it would be forever. Although ih it did take Penny a long time to tell Leonard that she loved him, she did admit her fear of the inevitability of their getting married in "The Tangible Affection Proof"; therefore, no "major" revelation occurred.
  • This episode aired on Kaley Cuoco's 32nd birthday, which was also the day she became engaged to Karl Cook.
  • When Bernadette talked to Penny about Howard and that he didn't think of him as a guy who does pervert thinks on the internet, Penny seems to understand what she's talking about. Actually, she learned about this from Howard at Season 4's fourth episode "The Hot Troll Manifestation". However, Zack appeared in the same scene whom Penny had broke up in Season 3's finale "The Lunar Excitation". This is the same episode where Amy and Sheldon met, while Penny met Amy at Season 4's premiere "The Robotic Arm Manipulation". So, if this scene is happening during "The Hot Troll Manifestation", Penny would recognize her "bestie", we saw in the last scene. So, that's the goof. The other scenario, is that this scene is happening during "The Lunar Excitation", or whatever episode did Penny got with Zack for the first time, so she dated him and didn't know Amy, but also didn't know the reason Bernadette and Howard broke up. So, whatever scenario is true, it's a goof.
    • Bernadette doesn't really elaborate on what Howard did she merely states he did weird stuff online. They don't get into specifics and Penny could have just assumed he was doing something totally different.
    • The flashback featuring Amy occurs before the second with Zack by at least a few months as she was still with Leonard as Sheldon states "He's desperate to hold on to you" Either way it's a goof as even if Penny didn't remember Amy, but Amy would no doubt remember Penny.
  • Mrs. Wolowitz accusing the boys of roughhousing (as this voice clip was reused from "The Bad Fish Paradigm") doesn't seem to make sense given how Leonard, Howard, and Raj were simply using the computer and talking at a regular volume. In that episode, she said so because Howard was angrily shouting at Sheldon.


Sheldon: Oh, Stuart, good. I was wondering, will you be accepting Bitcoin?
Stuart: Well, I don't know what that is, but it's got "coin" in it, and my cash register doesn't, so yeah.

Sheldon: I have grudges that go back to preschool. Someday, I'm gonna find a grown-up Elaine Dwyer and eat her favorite crayon while she watches.
Amy: Is that why there's an Elaine Dwyer on our guest list?

Penny: I thought you were looking at a cliff on the beach.
Amy: We were, but Sheldon didn't like any of them. Some were too beachy, some were too cliffy.
Sheldon: And all of them were too outsidey.

Howard: Do you think Zack stole it?
Penny: No, he doesn't know how to steal Bitcoin. I mean, he waves at trucks.

Sheldon: Hmm who could it have been?
Amy: Sheldon, what did you do?
Sheldon: I plotted my revenge. If you get a dish, I'll serve you some cold.

Stuart: I'm, uh, I'm running a special today, uh, buy something, keep having a comic book store to come to.

Penny: Hello Leonard. I was gonna write you an email, but I'm a little drunk and spelling is a sober person's game. I feel I owe you's planation. I'm sorry.Us planation.
Sheldon: Penny. {Knock-knock-knock}. Penny. {Knock-knock-knock}. Penny. {Knock-knock-knock}.
Penny: Sheldon, go away I'm making a video.
Sheldon: I'm sorry. I'll come back when you're alone.
Penny: No, no, no. I am alone. I'm just telling Leonard why I broke up with him.
Sheldon: Oh, he knows that. The video I want to see is why you went out with him in the first place.
Penny: I went out with him because he's great. If I kept going out with him I probably would have married him and it's a little scary because I don't think I'm ready for that. you know. Plus I have got to learn how to spell "Hofstadter" and I know there's a "D" in there but it keeps moving every time I try and write it. Sheldon what do I do?
Sheldon: Try to pass out face down so you don't choke on your vomit.
Penny: I am NOT gonna pass out, but thank you anyway.