The Feudalism Kid is a student at John Adams High. He just happened to be walking by when Shawn was really upset at how boring Feeny's feudalism lecture was, and he was slammed into a locker. He knew that Feeny had been teaching feudalism, though, and did not get angry at Shawn Hunter.
Later on, when Cory says the word "feudalism," a kid slams another kid into a locker in the background.
Because this character is credited with the name "kid," the title "Feudalism Kid" is considered non-canon.