Leonard: Here's your tea, Mother. So, what are you guys talking about?
Sheldon: The frequency with which your parents had intercourse.
Leonard: Swell. If you're lucky, maybe she'll show you the PowerPoint presentation.

Leonard: What would you be if you were attached to another object by an inclined plane, wrapped helically around an axis?
Sheldon: Screwed?
Leonard: There you go.

Leonard: Penny, as a scientist, my job is to figure out why things happen. But I don't think I'll ever understand how someone like me could get to be with someone like you. You know maybe I don't need to understand it, I just need to be grateful. I love you, Penny.

Sheldon: This song is never going to stop. Have you ever dealt with something so relentlessly irritating?
Leonard: That's a trick question, right?

Beverly Hofstadter: It might explain why the two of you have created an ersatz homosexual marriage to satisfy your need for intimacy.
Howard: Say what?

Leonard: She's only been here a day and a half, and I'm seriously considering alcoholism as a new career path.
Penny: Hey, I talked to her for five minutes yesterday, and I've been half bombed ever since.

Penny: I'm curious. What was Leonard like when he was little?
Beverly Hofstadter: I think you mean young. He's always been little.