Season 3, Episode 21: "The Letter"

Kramer, would you hold still? I can't do this if you keep moving.

You sure you don't want me to take my clothes off?

Because I'll do it.

No, that's the last thing in the world I want you to do.

Well, why don't you take your clothes off?

I don't know, I don't think Jerry would like that.

Well, it'll be our little secret.