The Pen is the first classic episode of Season 3, according to airing order. We first meet Jack Klompus and get our first glimpses of Florida.
Jerry gets himself in a lot of trouble when he takes a pen from his parent's neighbor Jack Klompus, which causes all sorts of problems, plus, Elaine has to sleep on an uncomfortable couch.
I think this is a great episode, from the opening to the end. It's quite different than what we're used to seeing. No George, no Kramer. It's quite weird. But definitely an example of classic Seinfeld. Hooray to Larry and Jerry and Season 3.