Sheldon: There are post-prom mating rituals?
Penny: Not always. Unless your date drives a van with an air mattress, then always.

Sheldon: Woman, you are playing with forces beyond your ken.
Penny: Yeah, well your Ken can kiss my Barbie.

Raj: [to Amy] If you were having Sheldon's baby, would you really want him in the room?
Penny: Yeah, if he's in the room when they're making the baby, I'll give you $10.

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?

Sheldon: I really did think you looked pretty.
Amy: You did?
Sheldon: Yes. So much so that I started to panic.
Amy: Well you can relax. Just because you think I look pretty doesn't mean we have to spend the night together.
Sheldon: Were you hoping we would because it's prom?
Amy: I'm always hoping. But tonight, I just wanted to have a nice time with you. Maybe dance with someone who has arms.

Sheldon: There's no denying that I have feelings for you that can't be explained in any other way. I briefly considered that I had a brain parasite, but that seems even more far-fetched. The only conclusion was love.

Stuart: Oh, so she's good enough for Howard but not for me?
Howard: Yeah.
Bernadette: Yeah. Go have weird relationships with your own mother and cousin. This is his turf.