This is a photo from "The Itchy Brain Simulation." It's Episode 7 of The Big Bang Theory Season 8.
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Sheldon looks unhappy with his dinner prospects on The Big Bang Theory. "The Thanksgiving Decoupling" is the ninth episode of the show's seventh season.
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It's Bob Newhart on The Big Bang Theory! This is a photo from "The Proton Displacement."
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Sheldon makes Leonard pays for a past mistake on The Big Bang Theory. "The Itchy Brain Simulation" is the eighth episode of the show's seventh season.
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Dr. Proton and Bill Nye the Science Guy both visit The Big Bang Theory. "The Proton Displacement" is the seventh episode of the show's seventh season.
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Sheldon feels like a fraud with his latest scientific breakthrough on The Big Bang Theory. "The Romance Resonance" is the sixth episode of the show's seventh season.
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Will Amy and Sheldon survive when they both at the university on The Big Bang Theory. "The Workplace Proximity" is the fifth episode of the show's seventh season.
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Sheldon vows revenge against Amy when she ruins his favorite movie on The BIg Bang Theory. "The Raiders Minimization" is the fourth episode of the show's seventh season.
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TBBT Quotes

Mrs. Cooper: Shelly! I'm so glad you're here!
Sheldon: I saw you having naked sex.

Penny: Here's a question-- as an alien pretending to be human, are you planning to engage in any post-prom mating rituals with Amy?
Sheldon: There are post-prom mating rituals?
Penny: Not always. Unless your date drives a van with an air mattress, then always.
Sheldon: Well, if it's part of the prom experience, then I'm open to it.
Penny: You're kidding.
Sheldon: I may be an alien, but I have urges.If Amy wants to copulate by firing her eggs into space, well, then, I will happily catch them with the reproductive sac on my upper flermin. I'm not the best at reading facial cues, but I can see that you're a little turned on.