JERRY: He got one of those Extension School degrees and thinks he's a big shot.

ELAINE: Extension School? I think my doorman went there.

[laughter]

JERRY: Oh hi, George.

GEORGE: Guess who I just saw down the street? Woody Allen. I think they're filming a movie.

JERRY: Did he go to Harvard, too?

[laughter]

GEORGE: Very funny.

ELAINE: You know, you didn't really go to Harvard.

GEORGE: Oh really? That's not what my degree says.

ELAINE: It's the Extension School, George.

GEORGE: So?

JERRY: Don't they have all those rules about how you can't put it on a resume?

GEORGE: No, they're just recommendations about how it should appear.

[laughter]

JERRY: Hello, Newman.

NEWMAN: Hello, Jerry.

[laughter]

NEWMAN: I couldn't help but overhear that George has joined the ranks of my fellow Harvard alumni.

JERRY: You went to Harvard?

NEWMAN: Yes, MES class of '86.

ELAINE: What's an MES?

NEWMAN: Master's of Extension Studies. It was a night program I completed before joining the Postal Service.

[laughter]

JERRY: Oh boy, now I've heard it all. I suppose you picked up a Ph.D. from Yale, too.

[laughter]

KRAMER: Come on George, we're going to be late!

ELAINE: Where are you guys going?

KRAMER: We've got a dinner at the Harvard Club.

JERRY: You too?

KRAMER: Extension School, Jerry. Extension School.

[laughter]

(http://www.autoadmit.com/thread.php?thread_id=5471194&forum_id=2#47269646)

Martin could take a class at HES just because he just wanted to learn about WWII or something he was interested in. Then, Frasier and Niles could get consumed by snobbery, try to talk him out of it, shame him for it, etc.

Niles went to Yale, so he could be like "Yale doesn't have an EXTENSION SCHOOL"

(http://www.autoadmit.com/thread.php?thread_id=5471194&forum_id=2#47269828)