Leonard: It must be hell inside your head.
Sheldon: At times.

Howard: Guys, we have a code red.
Sheldon: Do you mean code red for the hospital emergency alert, code red the computer worm, or Code Red the cherry-flavored soft drink from the makers of Mountain Dew?

Sheldon: I must say, Howard, I think a detailed letter to MIT describing your current circumstances might entitle you to a refund on your master's degree.

Leonard: Oh. It's Stuart.
Sheldon: You're not going to answer it?
Leonard: He wants to talk about Penny. I don't want to talk about Penny.
Sheldon: You're making an assumption. Perhaps the comic book store is on fire, and he needs your assistance.
Leonard: Why would he call me?
Sheldon: We don't know. And if you don't answer the phone, we can't know.

Sheldon: Answer the phone, Leonard.
Leonard: No! There, it went to voice mail.
Sheldon: Aren't you going to check your messages?
Leonard: No.
Sheldon: You have to check your messages, the leaving of a message is one half of a social contract which is completed by the checking of the message. If that contract breaks down then all social contracts break down and we descend into anarchy.

Leonard: Well, what are you gonna do?
Howard: I'm gonna figure out how to fix it, then I'll tell them.
Leonard: So, what do you need us for?
Raj: He can't figure out how to fix it.
Howard: Hey, you said you were gonna be supportive.
Raj: I'm trying, but you have to admit this is pretty damn funny.
Sheldon: I agree. It's the juxtaposition of the high-tech nature of space exploration against the banality of a malfunctioning toilet that provides the comic fodder here. Check your messages.

Raj: Okay, look. Instead of trying to reinforce this structure here, what if we just ran another line, bypass it entirely?
Sheldon: It won't work. The diameter of the tubing is insufficient.
Raj: What if we reposition the collection tank?
Sheldon: It won't work. No way to mount it.
Howard: Okay, here's an idea. What if I change my name and go live with my cousin and her husband Avi in Israel?
Sheldon: That could work.

Howard: Hang on, I think I've got this. Help me see if we can wedge this little piece of PVC behind the support rod.
Sheldon: You're overestimating the tensile strength of the substructure you're building.
Howard: Sheldon, I know what I'm doing.
Sheldon: If you knew what you were doing, there wouldn't be a space toilet where my coffee table should be.

Sheldon: What exactly does that expression mean, 'friends with benefits?' Does he provide her with health insurance?

Sheldon: You know, I'm given to understand that there's an entire city in Nevada devoted specifically to help people like Howard forget their problems. They replace them with new problems such as alcoholism, gambling addiction and sexually transmitted diseases.

Leonard: What were you doing at Penny's?
Sheldon: Well, we had dinner, played some games, and then I spent the night. Oh, and you'll be happy to know that I now have a much better understanding of 'friends with benefits.'

Sheldon: You know I'm in such a good mood I'm actually finding your tenuous grasp of the English language folksy and charming today.

Sheldon: Penny.
Penny: What?
Sheldon: I can't sleep.
Penny: Maybe that's because your hole is still open.

Sheldon: Penny.
Penny: Yeah.
Sheldon: Thanks for letting me stay here.
Penny: Oh, you're welcome sweetie.
Sheldon: Okay, I'm sleepy now get out.

Sheldon: There was a tall man from Cornwall
Whose length exceeded his bed.
"My body fits on it.
But barely upon it.
There's no room for my big Cornish head!"