Just a really, really, really fat person.
Man, that kid in gym class is one fat mother fucker!
In call of Duty Modern Warfare 2, the Fat Motherfucker has been named by it's inventor Valmer, for the "Juggernuts", the description was called upon the "Juggernuts" because of the amount of clothes they wear which make called by the name, Fat Motherfuckers.
Player # 1: Hey, where is the Fat Motherfucker?
Player # 2: He's hereee!, kill 'em Fat Motherfuckers
Player # 3: I just got raped by one of them, Fuck 'em
Player # 1: Wooohoo, we fucked 'em Motherfuckers ;)
What you yell out of your car window when you see a big fat lard ass dragging his hulking huge ass down the street or waiting for the loser cruiser to take him to his job at Mickey Dees or Taco Smell or Circle K.
You yell these words all together very fat,"Fatmotherfucker!!!" Then drive though a mud puddle splashing their brown polyester uniform with filthy water then roars off laughing.
Smell ya later
Lookit that fat fuck nut waiting for the bus, opens car window,yells out window
FATMOTHERFUCKER!!! Drives through large puddle splashes water on fat boy. Fat boy stands there covered in muddy water scratching,"What the Fuck???"
Assholes in car drive off laffing like hyenas.