Sheldon: Are you upset about something?
Leonard: What was your first clue?
Sheldon: Well, it was a number of things. First, the late hour, then you demeanor seems very low energy, plus your irritability.
Leonard: Yes, I'm upset!
Sheldon: Oh. I don't usually pick up on those things. Good for me.
Leonard: Yeah, good for you.
Sheldon: (walks away and then turns back) Oh, wait. Did you want to talk about what's bothering you?
Leonard: I don't know. Maybe.
Sheldon: Wow! I'm on fire tonight.

Leonard: Can I go back and prevent you from explaining that to me?
Sheldon: Same paradox. If you were to travel back in time and, say, knock me unconscious, you would not then have the conversation that irritated you, motivating you to go back and knock me unconscious.
Leonard: What if I knock you unconscious now?
Sheldon: It won't change the past.
Leonard: But it'd make the present so much nicer.

Penny: What the hell's going on?
Sheldon: You hypocrite.
Penny: What?
Sheldon: Little Miss Grown-Ups-Don't-Play-With-Toys! If I went into that apartment right now, would I not find Beanie Babies? Are you not an accumulator of Care Bears and My Little Ponies? And who is that Japanese feline I see frolicking on your shorts? Hello, Hello Kitty!

Penny: It is the things you love that make you who you are.
Wolowitz: I guess that makes me large breasts.

Leonard: How are we gonna get it upstairs?
Sheldon: If we take the dish off, it might fit in the elevator.
Leonard: Yes, but the elevator's been broken for two years.
Sheldon: I've been meaning to ask you, do you think we should make a call about that?
Howard: Not necessary, I have a master's in engineering. I remotely repair satellites on a regular basis. I troubleshoot satellite payloads. When the Mars Rover started pulling to the left, I performed a front-end alignment from 62 million miles away. (Pushing button on elevator) Nah, that baby's broken.

Sheldon: Well, this sandwich is an unmitigated disaster. I asked for turkey and roast beef with lettuce and swiss on whole wheat.
Raj: What did they give you?
Sheldon: Turkey and Roast beef with swiss and lettuce on whole wheat.
*The guys look at Sheldon*
Sheldon: It's the right ingredients but in the wrong order. In a proper sandwich, the cheese is adjacent to the bread to create a moisture barrier against the lettuce. They might as well have dragged this thing through a car wash.

Leonard: I just assumed. Who sells a full-sized time machine for $800?
Sheldon: In a Venn diagram that would be an individual located within the intersection of the sets 'no longer want my time machine' and 'need $800'.

Leonard: Come on, guys, push!
Howard: If I push any harder I'm gonna give birth to my colon.

Raj: Did the listing actually saying "Miniature"?
Leonard: (Looking at time machine) I just assumed.

Penny: I'm running really late (to work).
Sheldon: Then I have a simple solution: Go up to the roof, hop over to next building, there's a small gap, don't look if you suffer of vertigo, and use their stairwell.
Penny: You are joking, right?
Sheldon: Oh, I never joke when it comes to vertigo.

Penny: Oh, please, it's not a time machine, if anything, it looks like something Elton John would drive through the Everglades.
Sheldon: It only moves in time, it would be worse than useless in a swamp.

Sheldon: Oh, no, not Morlocks, not flesh eating Morlocks! Help!

Sheldon: Leonard, it's two in the morning.
Leonard: So?
Sheldon: So, it's my turn.

Sheldon: Why did you set it for the day before yesterday?
Leonard: Because I want to go back and keep myself from getting a time machine.
Sheldon: You can't. If you were to prevent yourself from buying it in the past, you would not have it available in the present to travel back and stop yourself from buying it, ergo you would still have it. This is a classic rookie time travel mistake.

Leonard: Uh, here's the thing. Girls like Penny never end up with guys who own time machines.
Sheldon: I disagree. Your inability to successfully woo Penny long predates your acquisition of the time machine. That failure clearly stands on its own.