If you can talk to them, you can ask them out.

Sheldon: I might as well explain the laws of thermodynamics to a bunch of labradoodles.

Sheldon: I weep for the future of science. Now if you’ll excuse me, the latest issue of Batman is out.

Raj: I love this time of the year. The leaves are turning, there’s a bracing chill in the air.
Howard: Plus there’s a whole new crop of female grad students about to put on just enough winter weight to make them needy and vulnerable. That’s right, honey, have another calzone, Daddy can wait.

Ramona:Oh, my God, that would change the way we view the entire physical universe.
Sheldon: It’s what I do.

Ramona: I already have your address.
Sheldon: What a nice girl.
Howard: Sheldon, do you have any idea what just happened?
Sheldon: Yes. Apparently I’m getting a free dinner.

Penny: What's Sheldon's deal?

Howard: I believe one day Sheldon will eat an enormous amount of Thai food and split into two Sheldons.
Leonard: On the other hand, I think Sheldon might be the larval form of his species, and someday he’ll spin a cocoon and emerge two months later with moth wings and an exoskeleton.
Penny: Okay, well, thanks for the nightmares.

Ramona: Your friends are holding you back.
Sheldon: I prefer to think of it as I’m pulling them forward.

Sheldon: Apparently I’m in some kind of relationship, and you seem to be an expert at ending them.

Ramona: I know what’s going on here.
Penny: Really? Well, then will you explain it to me?
Ramona: You’re in love with Dr. Cooper.
Penny: Uh, yeah, no, that’s not it.
Ramona: Don’t try to deny it. He’s a remarkable man, but you have to let him go.
Penny: Oh, gee, okay.
Ramona: I know it’s hard, but he’s a gift to the whole world, and we can’t be selfish.
Penny: Yeah, he’s a gift all right.

Penny: Holy crap on a cracker!