Sheldon: [bell ringing]
Lawrence: Uh... we need to talk.
Sheldon: About this bell? You got it. Did you know different engineers would often...
Lawrence: [stops bell] Son? You're a sweet kid, but... I don't think this is working out.
Sheldon: What? Why? I-I know everything there is to know about trains.
Lawrence: Well, yeah, you see now, that there is the problem. People, when they come here, they want to enjoy it. They don't want to get lectured in the bathroom. And you have been correcting me in front of the visitors all morning long.
Sheldon: Would you prefer I send you a memo of your mistakes at the end of the day?
Lawrence: No.
Sheldon: Because that's what I did for the teachers at my school. I think it brought us all closer.
Lawrence: Sheldon, it's great to have knowledge. But you don't need to show it off all the time.
Sheldon: Oh, I don't mind.
Lawrence: [chuckles] You see, trains are all about balance, right? Now you put too much water into a steam engine, it can't do its job. You let that water run low... Boom, it'll blow up. Now, a good engineer makes sure he uses just the right amount of water. Not too little, not too much. That make sense?
Sheldon: The fireman adjusts the water, not the engineer.
[later, as Meemaw drives Sheldon home:]
Sheldon: And then he took my "ask me" button. He didn't even ask me. He just took it.

Principal Petersen: Our next young speaker needs no introduction, but that didn't stop him from writing one and making me read it. [laughter] "Fun fact." [audience groans, murmurs] I hear you. "The word 'valedictorian' is from the Latin 'valedicere,' meaning 'to say farewell.' It is primarily used in the United States, Canada, the Philippines and Armenia." Maybe that fact's more fun in Armenia. Please welcome your valedictorian, Sheldon Cooper.
Mary: Yay, Shelly!
Sheldon: Hello. I'm not very comfortable speaking in front of crowds. But there's a technique to reduce stage fright by focusing on one person in the audience and delivering your speech just to them. That's what I'll be doing today. If it weren't for this person, I wouldn't be here right now. They've taught me a lot, and it's by their example that I found the courage to move forward into this new and exciting chapter of my life. Missy... ...this is for you. Change can be scary, but I know we're going to be fine... ...because like you said, "It's okay to be scared. We just have to do it anyway." So if any of my fellow graduates are nervous about the future, know that you're not alone. I suggest you all try to be as brave as my twin sister. That's my plan. Missy, I wish I could give you advice about middle school, but I was so smart, I skipped it. If you make it to high school, we'll talk. Thank you. [applause]

Mary: Sheldon, faith means believing in something you can't know for sure is real. And right now, I am struggling with that.
Sheldon: So you don't believe in God anymore?
Mary: That isn't something for you to worry about. I need to figure this out myself.
Sheldon: Can I help? Maybe I could provide a fresh perspective.
Mary: I don't think so, baby.
Sheldon: Did you know that if gravity were slightly more powerful, the universe would collapse into a ball?
Mary: I did not.
Sheldon: Also, if gravity were slightly less powerful, the universe would fly apart and there would be no stars or planets.
Mary: Where you going with this, Sheldon?
Sheldon: It's just that gravity is precisely as strong as it needs to be. And if the ratio of the electromagnetic force to the strong force wasn't one percent, life wouldn't exist. What are the odds that would happen all by itself?
Mary: Why are you trying to convince me to believe in God? You don't believe in God.
Sheldon: I don't, but the precision of the universe at least makes it logical to conclude there's a creator.
Mary: Baby, I appreciate what you're trying to do, but logic is here. And my problem is here.
Sheldon: Well, there are 5 billion people on this planet and you're the perfect mom for me. What are the odds of that?

Missy: What's it like to not believe in God?
Sheldon: It's great. Big fan.
Missy: Are you ever afraid you're wrong?
Sheldon: About religion? Never. About other things? Also never.

Adult Sheldon: Presenting... "Sheldon Cooper's Top Five Sources of News From My Childhood". Number five: Star Trek Fan Club Magazine.
Sheldon: Mom, DeForest Kelley's favorite episode is "The Empath."
Mary: Good to know.
Adult Sheldon: Number four: the Weather Cube from RadioShack.
Man: [from device] The humidity is 90% with a dew point of 79.5 degrees.
Sheldon: Mom! The dew point is 79.5 degrees.
Mary: [o.s.] Okay.
Adult Sheldon: Number three: The MacNeil/Lehrer NewsHour. Such a great theme song.
Sheldon: [hums] Buh-buh-bum.
Adult Sheldon: Number two: Meemaw after a few beers.
Meemaw: It took a while, but we finally picked a new name for my bowling team: The Ball Busters.
Sheldon: Hey, Mom. Guess what Meemaw named her bowling team? The Ball...
Adult Sheldon: And the number one source of news from my childhood: the bulletin board at the train store. News about trains in a store full of trains. Yummy.
Sheldon: How did this not make The MacNeil/Lehrer NewsHour?

George Jr.: So how many times have you seen Road House?
Mary: Sorry, can't hear you.
George Jr.: More or less than five? 'Cause that'show many times I've seen it.
Mary: That's how many years you're gonna be grounded if you don't drop it right now.
George Jr.: Does Dad know you like this movie?
Mary: [vacuum stops] No, and it is gonna stay that way.
George Jr.: Why?
Mary: Because it is not something I should be watching.
George Jr.: Then why are you watching it?
Mary: It is a guilty pleasure, so will you drop it now?
George Jr.: Relax. I ain't gonna tell nobody.
Mary: Thank you.
George Jr.: I think it's awesome you like it.
Mary: It is pretty cool how Dalton doesn't drive his Mercedes to the bar 'cause he knows they're gonna trash it.
George Jr.: Dalton's no dummy.
Mary: No, sir.

Mary: [eating pop corn] Get him, Dalton. Get him.
George Jr.: Mary Cooper, what are you doing?
Mary: Nothing.
George Jr.: Why are you watching Road House?
Mary: Why aren't you at work?
George Jr.: I asked you first, and my question is way more interesting.
Mary: It was just on. I don't even know what that is.
George Jr.: Then how'd you know his name's Dalton?
Mary: I don't have to explain myself to you.
George Jr.: This is a pretty dirty movie.
Mary: How do you know? It is rated R.
George Jr.: For violence, language and sexual content. You should be ashamed of yourself.