Adult Sheldon: I didn't realize until years later that my father was only asking questions about lightning and thunder to cheer me up. In fact, he would often pretend to be dumb just to make me feel better.

Mary: Wait, Georgie. Where's your bag?
Georgie: Don't need one. Got my toothbrush right here.
Mary: What about clothes? A change of underwear?
Georgie: Got it.
Mary: Georgie, you're gonna be gone for two days.
Georgie: I'll turn them inside out.

Adult Sheldon: I never did get to see a launch in person, but that was the best trip I ever had. I wish I had told my father while he was alive.

Mary: You're a good dad.
George: If I don't kill one of them before Sunday, I'm a good dad.

Sheldon: Schrodinger's cat is a thought experiment. A cat in a box is exposed to poison, and is both alive and dead until it is observed.
Georgie: So the cat's name is Schrodinger?
Sheldon: No.
Georgie: Well, what's its name?
Sheldon: Its name doesn't matter.
Georgie: It does if the cat was dead. Otherwise, what are you gonna put on his tombstone?
George: Not likely the cat's getting a tombstone.
Georgie: It would in a pet cemetery.

Sheldon: I wonder if we'll get to meet an astronaut.
Meemaw: I remember when I was a teenager, I had the biggest crush on John Glenn. I would've given it up for him no problem.
Mary: Mom.
Missy: Given what up?
Mary: Her allowance. Just eat.

Adult Sheldon: My plan was coming together. I just needed to get on the shuttle so I could finally escape this ridiculous planet. Spoiler alert, I'm still here.

Georgie: You might want to open a window.
George: Oh, boy.

George: Can I tell you a secret? I never understood how lightning works.
Sheldon: Didn't they teach you that in high school?
George: They probably did, but I got hit in the head a lot playing football. Would you explain it to me?
Sheldon: Well, when positive and negative charges grow large enough, a giant spark occurs in the cloud.
George: Ah, that-that's pretty cool. What causes the thunder?
Sheldon: It's a shock wave from particles heated to 10,000 degrees.
George: Interesting.
Sheldon: You want to know what's really interesting? Aristotle thought that the sound of thunder was due to a collision between two clouds. He believed the clouds were expelling air, in the way a log on a fire crackles-

Sheldon: Dad? Dad? Dad? - Dad.
George: What?
Sheldon: Georgie keeps kicking me.
George: Kick him back.
Sheldon: I'd rather not touch him.

[After Sheldon catches a fish]
Sheldon: Get it away, get it away!
George: Calm down, it's an itty-bitty thing.
Sheldon: No, I'm an itty-bitty thing!

[Sheldon, George Sr. and Georgie in a tent]
Sheldon: Moth! Moth!
George: Sheldon, it's just a butterfly.
Sheldon: How is that any better? Butterfly, butterfly!

Mary: Your hair's not changing color.
Missy: Aw.
Meemaw: Sorry, kiddo. Your mom is no fun.
Mary: Excuse me, I'm fun.
Missy: So I can color my hair?
Mary: Not a chance. But I'm very much fun.
Meemaw: Whatever you need to believe. Mein Fuhrer.

Sheldon: There is the launching of the space shuttle this weekend.
George: Space shuttle? Don't they do those out of Florida?
Sheldon: Yes. Cape Canaveral.
George: Sheldon, that's-that's like a 12, 15 hour drive.
Sheldon: I understand. Never mind.
George: You know what? Let's do it. It'll be fun. The three Cooper boys on a little adventure. Sound good?
Sheldon: Sounds good.

George: Yeah, I was thinking along the lines of something a little more active. Like last year, we went fishing-
Sheldon: Mom! Dad's trying to make me go fishing!
George: No, no, it's okay. We're not going fishing.
Sheldon: All right, good. But seriously, was fishing really that bad?
Sheldon: Mom! Dad's trying to convince me that fishing wasn't that bad!