Sheldon: [knocking] Missy?
Missy: What?
Sheldon: Sometimes I imagine that I'm an ion with a positive charge and they're an ion with a negative charge. It's so that whatever they say bounces off me and sticks to them.

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.

Lisa: [modem screeching] What's that noise?
George Jr.: No idea.
Sheldon: Georgie, I need you to get off the phone.
George Jr.: Hang on, Lisa. I'm helping someone with their English homework.
Sheldon: I don't have time for jokes. I need the phone line to connect my modem.
George Jr.: What the hell's a modem?
Sheldon: It links my computer to an interconnected web of other computers in order to facilitate the exchange of ideas.
George Jr.: That's the stupidest thing I've ever heard of.
Adult Sheldon: Sadly, that was not the stupidest thing he ever said.

Adult Sheldon: Thanks to Dr. Sturgis, I had all the intellectual ammunition I needed to bring my opponent to his knees. I accused him of conflating two different interpretations of quantum theory, woefully misrepresenting Paul Dirac, and when I called him a dung beetle in Latin, I was so riled up, I almost started producing testosterone.

Dale: Have you tried the meatballs here? They are fantastic.
Meemaw: I haven't. But speaking of meatballs, I hear you're gonna hang out with my son-in-law.
Dale: Yeah.
Meemaw: Hmm.
Dale: Oh. You don't like that at all.
Meemaw: No, it's fine with me. I hope you all go out and have a grand old time.
Dale: Oh. Yeah, well, what's the matter? You afraid I'm gonna find out all your secrets?
Meemaw: Calm down. You're enjoying this a little too much.
Dale: Enjoying it? I'm loving it. Look how mad you're getting. Come on, what's he got on you? Did you do some jail time? Were you a go-go dancer?
Meemaw: Hmm.
Dale: Have you got a tattoo in a naughty place? Can I see it?