Season 7, Episode 24: "The Invitations"

...and Kramer's the usher. What am I gonna be?

I don't think you're anything.

Well, I have to be something. I'm a close friend.

-What about being a bridesmaid? -Well, those are Susan's friends.

-Then how about being an usher? -All right, I'll ask Susan about it later.

You don't ask. You tell.