Leonard: Maybe I am her gay friend.

Sheldon: Is the whip sound app contextually appropriate here?
Leonard: Uh, it is, but I think you might have waited too long for it to be funny.
[whip cracks]
Leonard: [Everyone laughs] I was wrong; it was still funny.

Raj: Hey, want to spend some time playing the new Star Wars game this weekend?
Leonard: Oh, I don't know. I kinda promised myself I'd get off the computer, be more physically active, get some exercise.
Howard: You're about to walk up three flights of stairs.
Leonard: Good point. I'm in.

Leonard: I love cheesecake.
Sheldon: You're lactose-intolerant.
Leonard: I don't eat it. I just think it's a good idea.

Leonard: I'd love it if my dad could come.
Penny: Oh, you have to invite him. I haven't seen him since the divorce.
Leonard: Oh, he's like a different man. He stopped twitching, and I think he grew an inch and a half.

Wolowitz: Leonard, how was your date?
Leonard: Bite me!

Raj: How about Lasik?
Leonard: You want me to get eye surgery?
Raj: Would you rather go back to the apartment and deal with Sheldon or have a stranger carve out your corneas with a laser beam?
Howard: Well?
Leonard: I'm thinking.

Penny: Did we move at all?
Leonard: Maybe a long the Z axis, but X & Y are looking pretty sad.

Penny: Do they know why the pipes burst?
Amy: They didn't say.
Leonard: Buildings that have a combination of copper and galvanized steel are susceptible to pinholes and corrosion caused by the mobility of ions in the water. Can't have your head shoved in a toilet as much as I did and not pick up a few things about plumbing.

Penny: Now come on, we are gonna do this.
Leonard: Yeah. You get the paint, I'll rest for thirty to forty minutes, and then we do this.

Leonard: Congratulations. Who would've thought you two would be the first in our group to start a family.

Leonard: He made you his screensaver.
Amy: Oh, wow. I had no idea. He is so into me!

Leonard: I got you something for Valentine's Day and I was too embarrassed to give it to you.
Penny: Why?
Leonard: Because I got it at the dirty store.
Penny: You went to the dirty store without me?
Leonard: In sun glasses and a hat after I parked two blocks away.

Leonard: Never leave a belt on the floor. At night, they look like snakes.

Leonard: Sheldon, I've known you a long time. I'm going to tell you this with all the love I can possibly muster. Amy's right, you're wrong.
Sheldon: But you don't even know -
Leonard: It doesn't matter.
Sheldon: But in my defence -
Leonard: Doesn't matter!