The Imitation Perturbation is the sixth episode of the twelfth season of The Big Bang Theory.
While having dinner at the Hofstadter’s apartment, Raj mentions that it’s the fortieth anniversary of the movie "Halloween", though Sheldon doesn’t really understand what he’s talking about, and goes over the origins of the holiday. Amy asks if anyone is going to dress up at work. Bernadette tells them about the time someone dressed up as a zombie, causing a quarantine. Leonard proposes that they have a Halloween party. Howard says that he’s got a very scary costume.
As Sheldon walks down the corridor at CalTech dressed as Doc Brown from Back To The Future, Howard appears dressed as him. Sheldon is perplexed by the outfit.
Having lunch at the cafeteria, Leonard is dressed as Inspector Gadget while Raj is Supreme Court Justice Ruth Bader Ginsberg, or “Kooth Bader Ginsberg”. Howard turns up dressed Sheldon again and imitates him. When Leonard explains the reason for the costume, Sheldon doesn’t take it well.
As Sheldon is sulking in his office, Amy comes in, dressed as Clara Clayton. He tells her about Howard dressing like him, and wonders if he really does correct others.
At their apartment, now decorated for Halloween, Penny enters dressed like a sext pharmacist. She and Leonard talk about the last Halloween party they had.
Amy confronts Bernadette, and tries to get her to make Howard apologize, to no avail. She adds that Sheldon always teases Howard, and that he once called Halley “Winston Churchill”.
At the party, Anu is dressed as the United States Constitution, Stuart is a butterfly using one of Halley’s costumes, Bert is sporting a Doc Ewing outfit, Bernadette and Howard are Mary Poppins and Bert the chimney sweep, and Penny is dressed like a German barmaid. Leonard again tries to remind Penny of their first kiss. Sheldon and Amy enter dressed as Howard and Bernadette, and proceed to act like them and tease them, outraging them, while the others are slightly amused.
Driving home, Howard and Bernadette are still furious that Sheldon and Amy would get the gall to mock them like that. Howard reassures his wife that she has a melodious voice.
Penny admits to Leonard that she does remember their first kiss on Halloween as they’re cleaning up, but she feels that one doesn’t really count because she was mad at Kurt.
While Sheldon and Amy are having lunch, talking about how they got Howard and Bernadette good, Howard turns up and tells them that Bernadette was very offended when they taunted them and asks them to apologize; Amy first wants Bernadette to apologize for not making her husband apologize.
Sheldon meets with Bernadette and tells her that Amy wasn’t the first one to make fun of her voice. Bernadette states that she was picked on a lot because of her small stature, to which Sheldon says he can relate to that, because he was called egghead in high school. Bernadette is surprised that she and Sheldon have some things in common.
In Apartment 4A, Howard, Leonard, and Raj are about to present the first Halloween movie to Sheldon, when Amy arrives and declares that she is against Sheldon watching Halloween, and they go back to their place.
- The episode was released on the 40th anniversary of John Carpenter's Halloween.