Raj: I'd like to propose a toast to our friend, Howard. His, um, his big heart, his beautiful soul-
Leonard: And his tight little pants that somehow did not make him sterile.

Sheldon: No I should apologize. I never realized to what extent our friendship was a burden to you.
Leonard: That is not fair. I complain about what a burden it is at least once a month.
Sheldon: No, no, no. Let's not sugarcoat this. You find me finnicky, pedantic and annoying.
Penny: No, he doesn't.
Leonard: I have actually used those exact words before. In that order.

Amy: I've never seen him (Sheldon) this happy before.
Leonard: That's because you've never seen him on "Restock the Medicine Cabinet" day.

Howard: Wow. I wonder what that guy could've done to make Sheldon not talk to him for 20 years.
Leonard: I wonder if it'd work a second time.

Amy: Hey, did you guys know that Sheldon had a best friend growing up named Tam?
Leonard: Was that the imaginary talking koala?
Amy: No. He's a real person who apparently betrayed him.
Leonard: Yeah, so did the koala.

Leonard: "How are you with pets?" Well, I did take care of Sheldon for 15 years, and he only bit me twice.

Penny: You really want me to pick up your mother all by myself?
Leonard: Hmm, I just feel like it would be a good chance for you to bond.
Penny: Or a way for you to avoid her?
Leonard: I don't know what he's putting on those cards, but you are smarter than ever.

Leonard: Next question. Uh, "how close are you with your family?"
Penny: Pretty close.
Leonard: I'm gonna say not too close, but I'm hoping to get farther.

Leonard: Hang on. Are you feeling insecure? Because that's my thing, and if you take it away, I don't know what I'm bringing to this relationship.

Penny: Where's Sheldon?
Leonard: Oh, he was up late last night, so I gave him an early dinner and put him to bed.
Bernadette: That's so sweet.
Leonard: Yeah, but now he's gonna be up at dawn and want to play.

Leonard: You see, I used to be a jackass, but I stopped myself. I became a good guy. See, that's kind of my superpower. I'm like Captain Good Guy!
(Alice pushes him out, then slams door)
Leonard: It's okay. Did the right thing. *tightens his jacket* You idiot!

Howard: That was weird, right?
Leonard: Was it? I honestly can't tell anymore.

Priya: It's a little weird your ex-girlfriend hanging out here all the time.
Leonard: I know. I usually never see my ex-girlfriends, unless their hard drives crash.

Raj: I'm thinking about adopting some quirky affectation, like a pipe or a monocle or a handlebar moustache.
Leonard: For all those girls out there looking for the Indian Monopoly man?

Penny: How come you never eat broccoli?
Leonard: I'm married, I don't have to be attractive.