Oswald gets beaten up again! If you're playing the Oswald Drinking Game, take a drink. In fact, take two drinks, as he gets beaten up while trying to deliver a letter.
In this scene Kent unleashes what is probably the most extensive insult in all of Shakespeare. Here it is in its entirety:
[Thou art] a knave; a rascal; an eater of broken meats; a base, proud, shallow, beggarly, three-suited, hundred-pound, filthy, worsted-stocking knave; a lily-livered, action-taking knave, a whoreson, glass-gazing, super-serviceable finical rogue; one-trunk-inheriting slave; one that wouldst be a bawd, in way of good service, and art nothing but the composition of a knave, beggar, coward, pandar, and the son and heir of a mongrel bitch: one whom I will beat into clamorous whining, if thou deniest the least syllable of thy addition.
Meanwhile Oswald, who doesn't recognize Kent as the fellow who beat him up back at Goneril's place, is just totally confused. Come on, you have to feel for Oswald.
Kent, meanwhile, acts like a complete idiot. Here is his thought process: "What the best thing to do in the midst of a volatile and fragile family disagreement? I know! I'll beat up some guy and then insult lots of people! Nothing will go wrong!"
He totally deserves those stocks.