The Big Bang Theory recap: 'The Hot Tub Contamination' 

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It only took one quarrel over Sheldon’s insistence that Amy adhere to a strict bathroom schedule for

writers to reveal the story behind Sheldon’s three-knock quirk. His new roomie isn’t excited about her boyfriend regulating every aspect of her life. Sheldon can’t believe Amy won’t just roll over and accept her fate. Leonard and Penny take great pride in chanting, “No backsies” as Sheldon threatens to destroy the living space agreement. 

Realizing that he may be forced to evacuate his bowels every day at 7:12 a.m. again, Leonard understands the gravity of this fight. He and Penny work to convince Sheldon and Amy that they need to communicate better. Amy wants to store their toothbrushes in the same holder. This request makes Sheldon want to see other people. He assures Amy that the sexual creature within has awoken and he has an evolutionary drive that won’t quit. Ah biology, you saucy pervert. 

Penny takes Sheldon for a drive to cool off. She listens as Sheldon lists all of Amy’s shortcomings and finds herself agreeing with Sheldon because Leonard has the same issues. All that heavy breathing and complaining about people at work can get annoying.  And why do Amy and Leonard have to eye Sheldon and Penny like they are pieces of meat? Since when did appreciating the mind go out of style?

Meanwhile, Amy and Leonard have a similar conversation about their significant others. Leonard’s point? Sheldon is the worst. PS: Amy has never lived with anyone before and she starts with Sheldon?  Of course there needs to be a learning curve. Let him keep his chart in the bathroom that lists the number of days without her hair on the soap. That’s negotiable. 

While the Hofstadters play therapist, Raj and Stuart bid Howard adieu at the comic book store. He and Bernadette have plans to go to Palm Springs for a babymoon. What they didn’t plan on was morning sickness lasting well into the night. Howard suggests they take a staycation and just chill at the house. The others don’t have to know.

All is well until Howard hears someone come into the house. Since their phones are downstairs, they can’t call the police. Just as they begin to panic and try to figure out a way to email 9-1-1, Howard hears the hot tub fire up. He checks through the upstairs window to find Stuart bobbing in the foaming water like a boiled chicken breast. The scenario gets even more comical when Raj shows up, hops in the hot tub, and is scared out of his mind when Stuart pops up from the fathoms below.

Raj confesses to Stuart that he is single now. Bernadette feels bad that they didn’t know Raj’s relationship status. Howard reminds his wife that their friends live like squatters when they aren’t home, enjoying a spa day and free bottles of wine. All bets are off when Stuart refuses to leave with Raj due to the fact that he was hot tubbing commando this entire time. Howard shouts that the free loading is over to the surprise of his guests down below.

Back at the apartment, Leonard continues to praise Amy for all of the good things she has done in Sheldon’s life. Who got him to stop using Purell on his pocket change? Who got him to stop putting only gloves in the glove compartment? Why would she walk out on Pinocchio before he becomes a real boy? She can’t stop working on him now!

Over at an ice cream parlor, Penny finally gets to the bottom of Sheldon’s quest to find a new girlfriend. When he was thirteen, on Spring Break from college, he came home and found his father having relations with another woman in his parents’ bedroom. That’s why he always knocks three times. He locked eyes with his dad, ran to his room, and never spoke of it again. 

Penny understands Sheldon’s hesitancy: He’s trying to save Amy from pain down the road. Sheldon doesn’t want to turn into his parents by bickering all the time. Penny makes the suggestion that he try and fix the pain he’s causing Amy now instead of the future. He agrees and then apologizes for hurting Penny. How could he look for other women without considering her? 

Penny takes Sheldon back to Amy so he can make things right. He decides to forgo the bathroom schedule and reiterates that he was never interested in seeing other women. To prove it, he takes her across the hall and invites her to share a toothbrush holder with him. Call me crazy, but I teared up just like Penny. Our boy is growing up so fast. 

Sheldon: Look who’s open to compromise. The woman who married Leonard.

Leonard: Hey. She didn’t compromise. She settled. There’s a difference.

Howard: Pulling a quarter behind your ear isn’t the only magic these hands can do.

Sheldon: The first knock is traditional. The second and third knocks are to put your pants back on. 

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