After Bernadette receives a Ph.D and gets a well-paying job, the guys make fun of Howard for now having a future wife with a Ph.D while still being the only non-doctor in their group (sans Penny). Meanwhile, Raj becomes Sheldon's new roommate and Leonard moves in with Priya in Raj's apartment.
Leonard, Sheldon, Howard, Raj, and Priya are at The Cheesecake Factory. Bernadette comes by and announces she is getting her doctorate and the others start to mock Howard about his lack of a Ph.D. and he claims he is not bothered.
At his apartment, Raj hears Leonard and Priya getting ready for fun with a Star Trek cosplay|role-playing game. He is troubled by these activities, leaves, and attempts to sleep at Howard's, but Mrs. Wolowitz and her hormone replacement therapy make him uncomfortable.
Sheldon is video chatting with Amy when he hears a knock on his apartment door. It's Raj wanting to sleep|crash on Leonard's bed. Sheldon discourages it, but finally gives in and asks Raj to sign a waiver and gives him a safety drill. The next morning, Leonard enters his room and sits on his bed; to his surprise he discovers Raj sleeping in it. Raj explains his predicament and asks why Leonard can't sleep with Priya at his apartment, but Leonard says that she doesn't get along with Sheldon. He suggests that until Priya gets her own place in Los Angeles, Raj can stay at Leonard's and vice versa. Raj asks if he can bring girls to [[Leonard Hofstadter's bedroom|Leonard's room, and he agrees because he believes that Raj can't score with a girl and as long as they are there on their own free will.Later on, Raj gets Thai food, arranges it like a fancy dinner, and calls over Sheldon, who is amazed by the presentation. Penny comes over to ask if Sheldon changed his wi-fi password (the new one now being "pennygetyourownwifi"; no spaces), and she can't help but notice the fancy dinner. Sheldon tells her that Raj has replaced Leonard temporarily and that Leonard is now living with Priya. Howard and Bernadette are in bed together and Bernadette tells him that she got him a present. He opens it and it to find an expensive Rolex watch, and after the teasing from his friends they begin to argue.
Back at the apartment, Sheldon, Penny, and Raj are drinking and having dinner together. After Sheldon leaves to go to bed, Penny continues to talk to Raj, revealing her true feelings for Leonard and admitting that she never should have broken up with him, leaving Raj a little sad. In an attempt to comfort her, Raj tells her that her life is better than his of Internet pornography|downloading porn every night.
Leonard and Priya are making out when her parents call her for a video chat. Priya quickly asks him to go away so her parents don't spot him. Leonard overhears that Priya's moving back to India, he feels betrayed and, in the spur of the moment, he reveals himself by telling Priya's parents that they are dating.The next morning, Penny wakes up and discovers that she along with Raj are naked and to her horror realizes that she had sex with him. She tells him to act as if this hook-up never happened, he just nods as he still can't speak to her sober, which annoys her since they had been intimate.
Sheldon wakes up and finds Leonard on the couch, moping about Priya leaving for India and breaking up with him. Howard arrives at the door as he had a big fight with Bernadette because of the watch. Suddenly, Penny does the "walk of shame" out of Leonard's room with Raj close behind her, wrapped in a duvet. She panics and claims that "This is not what it looks like" and leaves. Sheldon then cluelessly asks, "What does it look like?"
- Guest starring:
- Teleplay: Bill Prady, Eric Kaplan & Jim Reynolds
- Story: Chuck Lorre, Steven Molaro & Eddie Gorodetsky
- The TV Critic "This was an interesting choice for a season finale. It was a mass of soap opera developments that many casual fans may have forgotten by next season. In most shows I wouldn't like that but I don't think it will harm The Big Bang Theory much. The show is still working on blending the soap opera in and I think these developments will allow next season to get rolling more quickly. The show remains flawed but funny and contrary to my expectations has improved this season."
- The A.V. Club gave this episode a B+.
- IMDb user reviews
- Title Reference: Raj replaces Leonard as Sheldon's roommate.
- Chuck Lorre's vanity card.
- This episode was watched by 11.30 million people with a rating of 3.6 (adults 18-49).
- This episode aired in Canada on May 19, 2011 with 3.448 million viewers and a weekly ranking of #1.
- In the United Kingdom, this episode aired on September 15, 2011 with 1.136 million total viewers and a weekly ranking of #14.
- Episode transcript 
- Penny and Raj's night together is later referenced in "The Hook-Up Reverberation" (S8E4), when his girlfriend Emily takes a disliking to Penny because of their "hook-up".
- Leonard mentions that he and Priya stay at Raj's apartment as she and Sheldon do not get along. This is following the events which occurred during "The Agreement Dissection" (S4E21).
- Leonard has two Star Wars figures on the stand in his bedroom, first seen in "The Precious Fragmentation". One is a Sideshow Collectibles Heroes of the Rebellion Han Solo in Stormtrooper Disguise Sixth Scale Figure and the other is a 15-inch Kotobukiya Chewbacca Pre-Painted Soft Vinyl Model. The Luke Skywalker in Stormtrooper Disguise Sixth Scale Figure that accompanies the former has been on the bookshelf next to the apartment entryway since "The Vengeance Formulation" (S3E9).
- The phosphorescence|luminous safety arrows haven't been seen in previous episodes when the lights are off. In "The Friendship Contraction" (S5E15), this issue is addressed when Sheldon implies that he has removed them, offering the explanation that the emergency glow-in-the-dark paint was wildly carcinogenic.
- When Raj set the dinner he light some candles. Sheldon does not point out that paraffin candles may contain carcinogenic, unless he assumes Raj's are soy based. Sheldon does make this point in "The Infestation Hypothesis".
- Leonard finally managed to convince Priya to wear Raj's Lieutenant Uhura uniform mentioned in "The Prestidigitation Approximation" (S4E18).
- Bernadette only features in two scenes with a different appearance in this episode.
- She is seen in her glasses and day-to-day wear in the opening Cheesecake Factory scene of this episode where she tells Penny, Priya and the men her exciting news about getting her PhD.
- She is seen with her glasses off and in her sleepwear in the bedroom scene at hers and Howard's apartment during this episode.
- The Rolex watch given to Howard by Bernadette is a Rolex President's, which cost around $25,000 at face value.
- Sheldon has a new wi-fi password, "pennygetyourownwifi". This action is part of an ongoing joke where Penny keeps using Leonard and Sheldon and Amy's wi-fi without paying. Sheldon makes no real effort to stop Penny from using the wi-fi, other than to criticize her for using it.
- When Sheldon has Raj sign a temporary roommate agreement, he awards him with an identity document|ID and lapel that sport the apartment's flag (the latter of which Leonard was "too cool to wear"), but he does not give him a flag as he did with Leonard. The apartment's flag is a gold lion rampant on a field of azure, as revealed in "The Staircase Implementation" (S3E22).
- After this episode Howard remains the only person who hasn't seen Penny naked. Sheldon saw her in "The Adhesive Duck Deficiency" (S3E8).
- Bernadette chooses not to do heart disease research since neither she nor Howard have it, even though in the previous episode Howard says his family is the "history of heart disease". Howard himself has transient idiopathic arrhythmia, as he mentions in "The Middle-Earth Paradigm" (S1E6), so it would seem he is at high risk. Howard mention his arrhythmia again after having sex with Lesley Winkle in "The Cushion Saturation" (S2E16).
- Last physical appearance of Priya in the show; she makes two subsequent appearances via Skype in Season 5.
- It really doesn't make much sense that a microbiologist would be studying premature ejaculation as it is not related to an infection.
- Leonard saying "Open the landing bay doors, shuttle craft approaching!" during sex with Priya is the most explicit sexual reference made in the series thus far.
- One time Penny does say to herself that Raj looks a lot cuter after she knows how wealthy his family is.
- In the previous episode "The Engagement Reaction", when Mrs. Wolowitz is in the hospital, Howard says that his family is the history of heart disease, and yet Bernadette dismisses the heart research because neither of them have any problems at the present time.
- Amy is not seen with any physical appearances with the gang in this episode and she is not sitting on the empty chair at the end of the table where Priya and the men are sitting in the opening Cheesecake Factory scene of this episode either (before Raj sits on it when they make Bernadette share the table with Priya and the other three men).
- This is the second season finale where Penny gets drunk and hooks up with one of the guys. The other episode is "The Lunar Excitation" (S3E23), when she hooks up with Leonard after breaking up with him.
- Raj: I'm the new homo in town. (realizes what he's just said) That came out wrong.
- Penny: (to Priya about Leonard) Yeah, a little tip, he says he can eat frozen yogurt, do not believe it!
- (Raj arrives at the Wolowitz residence and rings the doorbell. Howard opens the door)
- Howard: Hey, what's up?
- Mrs. Wolowitz: IS THAT MY FUTURE DAUGHTER-IN-LAW, THE DOCTAH?!
- Howard: NO, MOM, ITS RAJ!
- Mrs. Wolowitz: HE'S A DOCTAH TOO, RIGHT?
- Howard: YES!
- Mrs. Wolowitz: LIKE LEONARD AND THE SKINNY WEIRDO!
- Howard: SHELDON! YES, EVERYONE IS A DOCTOR BUT ME!
- Mrs. Wolowitz: AND WHOSE FAULT IS THAT?!
- Leonard: [finding Raj sleeping in his bed] What are you doing here?
- Raj: I was sleeping!
- Leonard: In my bed?!
- Raj: Well, I would have slept in my own bed, but it was being used to bring shame to my family... and the memory of Gene Roddenberry!
- (The scene of Howard and Bernadette’s bedroom in their apartment)
- Howard: So do you know what kind of research you’ll be doing at this pharmaceutical company?
- Bernadette: Well, there are a couple of opportunities available, but I volunteered for the premature ejaculation project. I mean, it’s not like either one of us has heart disease. Oh, I almost forgot. I got you a little present.
- Howard: Oh, Bernie, no. You didn’t have to.
- Bernadette: I wanted to. Come on, open it.
- Howard: You got me a Rolex. How much did it cost?
- Bernadette: You just let me worry about money. (Howard looks up, realizing what she said) I just want my baby to have pretty things.
- (scene: Leonard's bedroom. Camera pans over to all of the clothes lying around and eventually to Raj and Penny sleeping in Leonard's bed, with Raj's arm over Penny and both of them naked under the covers.)
- Penny: (wakes up) Oh, God. (both of them get up) OH, GOD!
- Penny: (In bed with Raj and horrified) OK, this never happened, do you understand??
- (Raj just nods)
- Penny: (Annoyed) Really?! Still can't talk to me?!
- Penny: (entering room disheveled, with a half-naked Raj behind) Damn.
- Leonard: What’s going on?
- Penny: Oh. It’s, it’s not what it looks like.
- Sheldon: (cluelessly) What does it look like?
- ↑ The Big Bang Theory - The Roommate Transmogrification (TV Episode 2011) - IMDb
- ↑ The TV Critic's Review
- ↑ The Big Bang Theory: "The Roommate Transmogrification" - TV Club - The A.V. Club
- ↑ Thursday Final Ratings: 'American Idol,' 'Big Bang,' 'The Office,' 'Grey's,' 'Mentalist' Adjusted Up - Zap2it
- ↑ Top Programs – Total Canada (English) May 16 – May 22, 2011 - BBM Canada
- ↑ BARB via Wikipedia
|Episodes | Season 4|