In two separate episodes of Seinfeld, George mentions his brother.
The first, in episode fifteen of the third season, titled "The Suicide":
RULA: Who’s Pauline?
GEORGE: Pauline? . . . Wait a minute. I got it. My brother once impregnated a woman named Pauline.
RULA: Do you think about her?
GEORGE: When I hear her name mentioned.
The second, in the twenty-third episode of the third season, titled "The Parking Spot":
ELAINE: Oh come on, George, please put it in a garage. I don't want to spend an hour looking for a space.
GEORGE: I can't park in a garage.
GEORGE: I don't know, I just can't. Nobody in my family can pay for parking, it's a sickness. My father never paid for parking; my mother, my brother, nobody. We can't do it.
Further confusing the situation is that in later episodes George repeatedly claims to be an only child. (examples welcome)
< seinfeldvoice >
So what's the deal with George Constanza's brother? Is he real, or is George an only child?
< / seinfeldvoice >