Welcome to comedy, Eliza Dushku. The actress appears as a FBI agent on The Big Bang Theory episode "The Apology Insufficiency."
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Leonard tries to keep an affair secret from Sheldon on "The Irish Pub Formulation." This is a scene from that episode.
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Amy has a request of Sheldon on the episode "The Desperation Emanation." She wants to introduce him to her mother.
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Who needs human companionship?!? Not Sheldon, this character hopes, on the episode titled "The Zazzy Substitution."
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How can Sheldon live longer? That's what he tries to figure out on the episode "The Cruciferous Vegetable Amplification."
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Say hello to Sheldon's nemesis on The Big Bang Theory: oh, yes, it's Evil Wil Wheaton!
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Sheldon requires a chaperon on his first date when season four of The Big Bang Theory kicks off. Penny is chosen for the job.
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Sheldon has a request for Penny on the fourth season premiere of The Big Bang Theory. Will she tag along on a date with him?
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TBBT Quotes

Sheldon: Why do you have the Chinese character for "soup" tattooed on your right buttock?
Penny: It's not "soup," it's "courage."
Sheldon: No it isn't. But I suppose it does take courage to demonstrate that kind of commitment to soup.
Penny: How'd you see it? You said you wouldn't look.
Sheldon: Sorry. As I told you, the hero always peeks.

Sheldon: Even the dung beetle chooses to plot its course by using the Milky Way.
Raj: Is that true?
Sheldon: Everything I say is true. Now, of course, the dung beetle also enjoys eating fece, living in feces and making little balls out of feces. So, pick and choose which aspects of its lifestyle you want to embrace.