S01E07
-Penny: Do you mind if I stay here tonight?
-Leonard:No, take the couch, or my bed. I just got new pillows. Hypo-allergenic.
-Penny:The couch is good.
-Sheldon:Hold that thought. Leonard, a moment.
-Leonard:Let me guess. You have a problem with this.
-Sheldon:Where do I begin?
-Leonard:It's up to you. Crazy person's choice.
-Sheldon:Well, first, we don't have houseguests. Frankly, if I could afford the rent, I'd ask you to leave.
-Leonard:Your friendship means a lot to me as well. What else?
-Sheldon:Well... our earthquake supplies.We have a two-man, two-day kit.
-Leonard:So?
-Sheldon:So if there's an earthquake and the three of us are trapped here, we could be out of food by tomorrow afternoon.
-Leonard:I'm sorry, are you suggesting that if we let Penny stay we might succumb to cannibalism?
-Sheldon:No one ever thinks it'll happen until it does.
-Leonard:Penny, if you promise not to chew the flesh off our bones while we sleep, you can stay.