Season 5, Episode 7: "The Nonfat Yogurt"

Hurry, Jerry, hurry!

How's it doin'?

Well, you can't have this tested now. It's melting.

It changes the molecules.

Oh, you don't know what you're talkin' about.

Hey, fatso, I got a 90 in biology.

You call me fatso one more time,

you're gonna be walkin' back.