Penny hugs Leonard after he does his best to comfort her after he ex reveals intimate details about her on his blog.
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.
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.

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