The Implant - S4-E19
Timmy: What are you doing?
George: What?
Timmy: Did...did you just double-dip that chip?
George: Excuse me?
Timmy: You double-dipped the chip.
George: Double-dipped? What are you talking about?
Timmy: You dipped the chip, you took a bite...and you dipped again.
George: So?
Timmy: That's like putting your whole mouth right in the dip! From now on, when you take a chip, just take one dip and end it.
Jerry: Hello?
Telemarketer: Hi, would you be interested in switching over to TMI long-distance service?
Jerry: Oh, gee. I...I can't talk right now. Why don't you give me your home number and I'll call you later?
Telemarketer: Uh...well, I'm sorry. We're not allowed to do that.
Jerry: Oh, I guess you don't want people calling you at home.
Telemarketer: No.
Jerry: Well, now you know how I feel.
Stu Chermack: What do you think the real problem is?
Rita Kirson: It's Seinfeld. He can't act. It's pathetic. I told you, these stand-ups can't act. I'm cringing watching him.
George Costanza: What if the pilot gets picked up and becomes a series?
Dana Foley: That would be wonderful, George. You'll be rich and successful.
George: That's exactly what I'm worried about. God would never let me be successful. He'd kill me first. He'll never let me be happy.
Dana: I thought you didn't believe in God.
George: I do for the bad things.
Dana: Do you hear what you're saying? God isn't out to get you, George. What What is that on your lip?
George: What?
Dana: It's like a discoloration. It's white.
George: [Looking at his reflection] Yes. Yes, it's white. Why is that white?
Dana: You better get that checked out.
George: "Better get that checked out"?
Dana: I would.
George: What kind of a therapist are you? I'm telling you I'm scared that something terrible is going to happen to me, right away you start looking for tumors?
The Virgin - S4-E10
Elaine: Look at George. He lucked out, huh?
Jerry: Oh, you're not kidding. Who'd have figured Susan would break up with him? They had a good thing going.
Elaine: Yeah. Since she met him, she's been vomited on, her family's cabin's been burned down, she learned her father's a homosexual, and she got fired from a high-paying network job. Yeah, they had a real good thing going.
[Jerry and Elaine found out that the TV that they gave to Drake and his girlfriend was given to his girlfriend after they broke up.]
Jerry: We're not getting that TV back.
George: What do you mean? I mean you gave it to them, we get it back.
Elaine: The Drakette took it.
George: She can't take it. It's not hers, it's theirs. Once there's no theirs, there's no hers. It should be ours.
Chosen answer: George does mention his brother in the episode "The Parking Space". They actually really never mention anything that contradicts the fact he had a brother though, it just isn't mentioned.