The Big Bang Theory Season 1 Episode 17
The Tangerine Factor
Penny breaks up with her boyfriend after he posted intimate details about her on his blog. Leonard tries to comfort her but accidentally sends her back into the arms of her boyfriend. When she returns she screams at Leonard as she explains her ex has already moved on!
As Penny laments her choices in men, Leonard awkwarldy asks her out on a real date. Penny thinks about it and agrees! After a few days past, Leonard and Penny begin to worry their date will ruin their friendship and both seek Sheldon's advice. Sheldon advises both of them using the Schrödinger's cat paradox basically telling them both to go for it or else you won't know the outcome.
When Leonard goes to pick Penny up for the date she says they need to talk. When Leonard asks her if she's heard of Schrödinger's cat and she says yes, he passionately kisses her. She says, "the cat's alive," and they leave for dinner.
Meanwhile, Sheldon asks Wolowitz to help teach him Mandarin because he thinks the local Chinese restaurant is giving him "Orange Chicken" instead of the "Tangerine Chicken" he is ordering. He becomes terrible at Mandarin and has several humorous translations as he attempts to order. Leonard and Penny almost go to the Chinese restaurant for their date but end up leaving when they see Sheldon fighting with the owner.