Sheldon: Missy! You gave me your yips.
Missy: What?
Sheldon: I froze on a test. That's never happened before. It's all your fault.
Missy: I told you it's not contagious.
Sheldon: You put the thought in my head. The power of suggestion is very real. Case in point: tulip mania.
Missy: Here we go.
Sheldon: Tulip mania was an insane desire to buy and trade tulip bulbs in the 1600s. It nearly ruined the Dutch economy. You would not believe the gilders they were spending.

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: Let's say grace.
Sheldon: Hang on, safety first. [puts mittens on]
George Jr.: When are you gonna get over that?
Sheldon: I would think recent events would make you value protection.
Mary: Enough.

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 Sr.: Look. I know you don't respect what I do as a coach.
Sheldon: Maybe you do know me.
George Sr.: But this is a thing I actually know about. I've seen it happen to my players. I've seen it happen to pros in golf. In baseball. The answer is always the same. Stop thinking and get out of your own way.
Sheldon: I don't know how to do that.
George Sr.: Have you ever heard the Nike slogan "Just do it"?
Sheldon: I'm familiar with the phrase "let's do it," uttered by Gary Gilmore, the last person to be executed by firing squad in America.
George Sr.: Okay, well, it's a shoe slogan. And it's good advice. The answer is already in your head. Don't think so hard. Just do it.
Sheldon: I'll try.
George Sr.: Good man.

Adult Sheldon: Of all the tests one takes in school, my favorite was the midterm. Finals weren't bad, but they also meant summer was approaching. I don't believe in religion, but sunshine, picnics and pool parties are proof hell exists.

Sheldon: I can't remember what the zeroes of the Bessel function are.
Dr. Linkletter: You didn't memorize them?
Sheldon: Of course I did... October 7th, 1988. I had just had a bowl of Teddy Grahams.
Dr. Linkletter: Then what's the problem?
Sheldon: I'm blanking, but I'll get it.
Dr. Linkletter: Sorry, son, class is over.
Sheldon: No, I can do this.
Dr. Linkletter: It's just one question. You'll still pass.
Sheldon: Sheldon Cooper doesn't "just pass."
Dr. Linkletter: I have an idea. Let me see the test. [Sheldon hands him the test] Thank you.
Sheldon: Sheldon Cooper isn't always that gullible.
Dr. Linkletter: He was today.