Penny hugs Leonard after he does his best to comfort her after he ex reveals intimate details about her on his blog.
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Wolowitz teaches Sheldon Mandarin so he can correctly order his Chinese food to make sure he gets tangerine instead of orange chicken. Makes sense to us.
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Leonard and Penny are about to kiss in this still. Leonard finally asked out Penny on a real date after she was hurt by her ex.
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The Big Bang Theory Season 1 Episode 17 Quotes

Penny: Maybe we should talk first.
Leonard: Okay, but before you say anything, have you ever heard of Schrödinger's cat?
Penny: Actually, I've heard far too much about Schrödinger's cat.
Leonard: Good.
[Leonard kisses Penny]
Penny: Alright, the cat's alive. Let's go to dinner

Leonard: I'm her friend, I'm not going to take advantage of her vulnerability.
Wolowitz: Wait, so you're saying that if in the depths of despair she throws herself at you and demands you take her right there, right now, you'll just walk away?
Leonard: I said I'm her friend, not her gay friend