Mary: Shelly, if you don't mind me asking, what's your long-term plan here?
Sheldon: I'm working on the math to turn the garage into a self-sustaining ecosystem.
Mary: Okay. And what exactly does that mean?
Sheldon: Well, all I need is sunlight and a few seeds to grow unlimited food which I'll fertilize with my own feces.
Meemaw: This just gets better.

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]

Sheldon: Missy and I broke a lot of rules the other night, and we've received no punishment.
George Sr.: [sighs] Buddy, it's been a rough week. We're just glad you're both safe.
Sheldon: But in the absence of a divine being, society's rules are what keeps a person's morality in check.
George Sr.: Well, there you go.
Sheldon: No, y-you're not following me. If actions have no repercussions, society breaks down, everything devolves into chaos.
George Sr.: You might be overthinking this.
Sheldon: I thought so, too. Then I thought about it, and I'm not.
George Sr.: Sheldon, you had one bad night. Just let it go.
Sheldon: But... I did something wrong and I got away with it. That's not okay.
George Sr.: Buddy...
Sheldon: Socrates maintained that the man who lies to himself has an enemy living within. He's not even a person. He's just a chaos of selfish desires wrapped in an animal hide.

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.

George Jr.: I think the saddest part about it is just how sad it is.

Adult Sheldon: As you can see, my meemaw successfully lured me back into the world by reminding me of my brave Texas ancestors. Their blood ran through my veins. I was a true son of the Lone Star State. Albeit a true son with an incredibly fragile immune system. I woke up the next morning with a temperature of 102 and a head packed full of mucus.

Meemaw: Mind if I take a crack at catching the Road Runner?
Mary: What are you gonna do that I couldn't do?
Meemaw: Oh, a little trick I learned trying to get prairie dogs out of the hole. Of course we'd whack off their heads with a golf club. I'm not gonna do that to Sheldon.