*Leonard is kissing Penny, and Penny's dad enters*
Penny: Come on, honey, not in front of my dad.
Penny's dad: Relax, I've seen her do a lot worse with a lot stupider.

Leonard: If I take it off, Sheldon wins.
Penny: Sweetie, every night you don't kill him in his sleep, he wins.

Penny: I mean, who even reads Scientific American?
Leonard: It's kind of a big deal.
Penny: If it's such a big deal, how come the biggest celebrity they could get for the cover is a molecule?

Howard: I'm not signing a prenup.
Penny: All right, Howard Wolowitz, listen up! You sign anything she puts in front of you, because you are the luckiest man alive. If you let her go, there is no way you can find anyone else. Speaking on behalf of all women, it is not going to happen, we had a meeting.

Leonard: You'll never guess what just happened.
Sheldon: You went out in the hallway, stumbled into an inter-dimensional portal, which brought you 5,000 years into the future, where you took advantage of the advanced technology to build a time machine, and now you're back, to bring us all with you to the year 7010, where we are transported to work at the think-a-torium by telepathically controlled flying dolphins?
Leonard: No.
Sheldon: Awww.
Leonard: Penny kissed me.
Sheldon: Who would ever guess that?

Sheldon: I'd like to go over some proposed changes to the roommate agreement, specifically to address Penny's annoying personal habits.
Penny: Oh my God! What personal habits?
Sheldon: I have a list. FYI overuse of the phrase "Oh my God" is number 12.

Howard: Don't be oversensitive. He's calling you illiterate, not your race.
Raj: Oh, okay. Good.