Sheldon: I know why the song was in my head.
Penny: Why?
Sheldon: It's about Amy.
Penny: Okay, look, I know Amy's like an old lady, but she's not old enough to have a song from the '60s written about her.

Howard: You know what's really happening here? Your girlfriend is breaking up our band.
Raj: She has nothing to do with this. I am my own man.
Howard: Oh, please. Your brain belongs to whoever's willing to sleep with you.
Raj: That is so not true.
Howard: Really? Remember when you were gonna get circumcised for Rachel Bernstein?
Raj: That had nothing to do with Rachel. It was an overreaction to a bad zipper injury.

Howard: If you don't want to use dating Web sites, what do you suggest?
Sheldon: Off the top of my head? Prospective women weed themselves out in a battle of wits until only one champion remains, she shows up at my door flush with the thrill of victory, and then sits quietly by my side while I watch Daredevil.
Howard: You seriously think women would fight for you?
Sheldon: People compete for jobs and trophies, why not me?
Howard: He's right. He knows a lot of jokes.

Leonard: Penny. We are made of particles that have existed since the moment the universe began. I like to think those atoms traveled fourteen billion years through time and space to create us, so that we could be together and make each other whole.

Bernadette: Come on, it could be romantic. The two of them away together, keeping each other warm in snowy Wisconsin.
Sheldon: Oh, no, no, no, no. She'd be going alone. If you think I'm scared of birds, you should see me around sheep.

Sheldon: Well, this is different. Candles and music.
Amy: Do you like it?
Sheldon: It's kind of spooky.
Amy: I can change it back.
Sheldon: No, it's your birthday. As long as no one jumps out in a hockey mask, I'll be fine.

Amy: Uh, well, actually, to be honest I haven't told her yet.
Penny: You've been giving me a hard time and you haven't even told your mom about Sheldon?
Amy: I'm feeling a little dizzy from all the blood loss. I don't know what you're talking about.

Leonard: I can't believe I'm spending my wedding night with you.
Sheldon: Really? I never imagined it any other way.

Bernadette: Aww, that was beautiful.
Howard: Yeah. I mean, not like our wedding beautiful.
Bernadette: No, we totally won.

Sheldon: She watched it. I'm gonna get that girl back.
Amy: I only watched it because you emailed it to me with the subject line "This is gonna make you mad."
Sheldon: She was listening through the door. She wants me.

Sheldon: Well, I enjoyed that more than I thought I would.
Amy: Me too!
Sheldon: I look forward to your next birthday when we do it again!
Amy: That works for me.

Penny: Well, what's the third option?
Sheldon: That I have coitus with her.
(Penny's wine glass smashes in her hand)

Sheldon: This is Leonard. He's your best friend in the world.
Leonard: All right, just stop. This is ridiculous.
Sheldon: Sometimes he gets cranky, but you can trust him with your life. And he does more things for you than I can even begin to list.
Leonard: Thank you.

Sheldon: Amy, there was a song I couldn't get out of my head. Eventually, I realized the song was about you, and like that earworm, I can't get you out of my heart. So, what I'm trying to say is, you're my heartworm. The metaphorical kind, not the poodle-killing kind.

Raj: Look at that. You've known you're gonna be a father for less than a day and you're already stepping up.
Leonard: I'm telling you, you got this.
Howard: Maybe you're right.
Sheldon: Of course he's right. You and I both know how hard it is growing up without a father. That's why I'm confident you're gonna be the best dad you can be.
Howard: Thank you, Sheldon.
Sheldon: You're welcome. And if he has twins, we can do all kinds of neat experiments on them.