After a night dancing, Amy kisses Sheldon. It's their first kiss!
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Sheldon and Amy do a scientific evaluation when she gets turned on by Zach. They determine that she's horny. He wants her to go out with Zach, but instead she tries a hand-holding experiment with Sheldon.
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Don't look for Leonard and Priya to slow down on season five. Not even 7,500 miles can end their relationship!
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Raj and Penny looked as shocked by their actions here as viewers of The Big Bang Theory were. They slept together?!?
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Cheers to a new set up. Raj moves in with Sheldon on the season finale of The Big Bang Theory.
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Sheldon makes a grave mistake in this scene: he drinks from Leonard's glass!
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There is only one Raj.
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Sheldon busts a move on TBBT. Instant fun ensues.
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The Big Bang Theory Season 4 Quotes

Penny: Hey, Sheldon, did you change your Wi-Fi password again?
Sheldon: Yes, it's "Penny, get your own Wi-Fi." No spaces.

Leonard: Hi. I'm Leonard. You are beautiful. You pop, sparkle and buzz electric. I'm going to pick you up at eight, show you a night you will never forget.
Raj: Where are we going?