A kid that takes gym too seriously, usually they are jocks and they will yell at you if you don't do shit.
Me talking to friend: Dude what was the Geometry homework again?
*Gym class hero (a senior on the football team) smashes into friend, breaking his arm.*
Friend: Oh fuck my arm hurts like a bitch owwwwwwwwww.
Gym Class hero: That's what you get for not catching the ball.
Me: Go fuck your disgusting girlfriend gym class hero.