As the second series of Seinfeld comes to its end, Julia Louis-Dreyfus shows her full potential by stealing the entire show with just one scene. And she isn't even part of the main story! No, that bit of the episode involves George, who inadvertently got a busboy fired from a restaurant and tries to apologize with Kramer's "help", only to make the matter much worse. Meanwhile, Jerry just stays in his apartment listening to everybody's problems, particularly Elaine's attempts to get an annoying boyfriend out of her apartment.
It is the latter event that marks the comedic high point of The Busboy, all thanks to Louis-Dreyfus' hilarious desperation (used to great effect in subsequent seasons as well) and ace line-delivery (the most inventive list of excuses since John Belushi's monologue in The Blues Brothers). In one brief moment, she shows exactly how self-absorbed and shallow she can get, and audiences love her for that.
That single sequence nearly sucks all the energy out of the episode; fortunately, that is not the case, with George and Kramer's encounter with the busboy being a milestone in the show's "awkward situations" list. It is a memorable event especially because it contains two firsts on Kramer's CV: it's the first time he's out of his apartment (after 15 years, if we are to believe Jerry's words in the pilot), and also the first time he speaks Spanish, a recurring joke that enabled Michael Richards to combine his astounding physicality with astute wordplay, spawning a lot more classic scenes.
A little thing worth noticing: technically, this isn't the season finale (it's The Deal, but the last four shows of Season Two aired in the wrong order), but it doesn't really matter; Seinfeld remains unmissable nonetheless.