Leonard: Okay. So Wolowitz and Stuart are paralyzed, Santa’s dead, and I picked this over having sex with my girlfriend.

Leonard: My dad was an anthropologist. The only father-son time he spent was with a 2,000-year-old skeleton of a Etruscan boy. I hated that kid.

Howard: (Slams his car door) Will you please talk some sense into your lunatic roommate?
Leonard: You're both acting like lunatics!

Leonard: Who are you talking to?
Penny: Oh, just this guy I met at school.
Leonard: oh, great. We're still dating, right?
Penny: Relax. He's just a friend. We're doing an oral report together. He's really nice.
Leonard: I'm sorry, what was that? I had a little stroke after oral.

Penny: What am I supposed to say?
Leonard: Say "Can't talk right now, hanging with my boyfriend. England sucks. You suck. USA number one."

Leonard: You, uh, moving in to the apartment on the fifth floor?
Cole: No, I was just visiting a friend.
Leonard: Oh, cool. The cute blond on four?
Cole: Yeah, you know her?
Leonard: I see her around. I like to keep my distance because her boyfriend is a pretty scary dude.
Cole: Really?
Leonard: Yeah. He's ganged up.
Cole: She told me he's a scientist.
Leonard: That's the name of his gang. The Scientists. They're crazy.
Cole: Well, thanks for the tip.
Leonard: No problem, brother. Stay frosty.

Alex: Oh, hello, Dr. Hofstadter.
Leonard: Hey, Alex, call me Leonard. Dr. Hofstadter is my father. And my mother. And my sister. And our cat. Although I'm pretty sure Dr. Boots Hofstadter's degree was honorary.

Leonard: Please be good, please be good. Uh-huh, uh-huh. Okay, she writes like she cooks.

Leonard: It's like when I started doing chin-ups. I didn't want you to see until I could do one. FYI, really close.

Penny: Okay, listen, there's something I need to tell you. I've been thinking about going back to school for a while now. So a couple months ago, I started taking a history class at the community college.
Leonard: Oh. That's great. Great, great, great. Why wait so long to tell me?
Penny: I don't want you to make a big deal out of it.
Leonard: Why do you think I'd be like that? I get it, you're taking one class. It's nice. Maybe if it goes well, you take another, you enroll full-time. Ooh, be sure to keep an eye on which credits transfer to a four-year college.
Penny: You're making it a big deal.
Leonard: Sorry. (nonchalantly) Whatever. It's all good.

Penny: Now behave yourself and eat your dinner. Maybe later, if you're lucky, you get to sleep with a college girl.
Leonard: Really? 'cause I went to four years of college and five years of grad school, that never happened once.

Penny: So, what ya doing? Better not be building a robot girlfriend.
Leonard: No. Although Howard was making some real strides in that area until he met Bernadette.
Penny: You're kidding.
Leonard: Nope. Now the Lisatronic 3000 just sits in a box waiting for the phone to ring.

Leonard: It's kind of crazy. I've never fooled around in the lab before.
Penny: Really? Never?
Leonard: No. I did have a shot with the Lisatronic, but the extension cord wasn't long enough.

Leonard: Oh, you don't have any jewelry on, do you?
Penny: No. Why?
Leonard: A grad student forgot to take out one of his piercings. Now he's on a transplant list waiting for a nipple his size.

Penny: Oh, my God, you guys look adorable.
Bernadette: Thanks, so do you. Slutty cop?
Penny: No, sexy cop. Slutty cop only came with a skirt and two badges.
Bernadette: And Albert Einstein?
Leonard: Ja, und later zhe's going to arrest me for goinc fashter zan da shpeed of light.
Penny: I thought we said in the car, no accents?
Leonard: Sorry, Officer.