Sheldon: Leonard, quick. I need you to get me to Arcadia within the hour. The train store's having a sale.
Leonard: Why can't Amy drive you?
Sheldon: Because of the tradition that I cannot see Amy on the day of the train store sale.
Leonard: Please, please see a doctor.

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: 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.

Leonard: Thank you for seeing me on such short notice.
Dr. Gallo: Ah, it's my pleasure. I'm curious, are you related to Dr. Beverly Hofstadter?
Leonard: Uh, she's my mother. You know her?
Dr. Gallo: No, not personally, but I have read all of her books.
Leonard: Well, then you know her better than I do.
Dr. Gallo: Well, I'm not so sure about that. But I can tell you I do not agree with her theories on child rearing at all.
Leonard: Really? Any chance you find them cold, cruel and unsuitable for innocent little boys who just want to be happy?
Dr. Gallo: Well, I didn't want to say it-
Leonard: No, no, say it. Sing it. Rent a plane, write it in the sky.

Penny: Okay, what just happened?
Leonard: I don't know. Between you playing chess like Bobby Fischer and Sheldon being okay with you in his spot, I'm guessing someone went back in time, stepped on a bug, and changed the course of human events.

Leonard: That's actually a valid example. Animals do deliver messages through scent.
Raj: Bees talk to each other by dancing. Whales have their songs.
Leonard: Penny has about 20 different ways of rolling her eyes that each mean something different.

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: On the count of three, both of you bounce the balls as hard as you can. The highest bounce wins the office.
Barry Kripke: Oh, you are going down, Cooper.
Sheldon: I don't think so, Kripke. I've bounced many a rubber ball in my day.
Leonard: All right, that's enough trash talk. One, two, three.

Leonard: Well, now hold on, how about this? How about we still hang out, but on the down-low?
Penny: Are you really that kind of guy?
Leonard: No. I actually felt kinda silly just saying on the down-low.

Howard: You're still working on Sheldon's dumb brain teaser?
Leonard: Oh, my God, Dr. Purple's a woman! Of course! Oh, that feels so good.

Penny: So we're about to film this scene in the movie where the killer ape DNA is slowly taking over my body.
Leonard: Okay.
Penny: But I realize they're gluing fur everywhere except my cleavage. So I ask the director and he says it's important to the story that my boobs be the last things to turn ape.
Leonard: It's sweet that he thinks there's a story.

Sheldon: Can I at least kick down the door?
Leonard: You're welcome to try, but the other day, it took you 15 minutes to get into a FedEx box.

Penny: All right, this is making me crazy. Somebody's got to go over there.
Leonard: You got feet and legs, you do it.

Raj: Maybe moving in was a bad idea. I haven't been here one day, I'm already causing problems.
Penny: You didn't do anything. It's Sheldon.
Leonard: "You didn't do anything.It's Sheldon." That'd make a nice needlepoint pillow.

Leonard: Ladies do love a guy dressed like a kitchen garbage bag.