To be a fanmog, one must first be a fan of Japanese culture since Final Fantasy is Yaoi and all of the male characters are ambigiuously gendered and completely androgynous.
Someone who is secure with being overweight. A fat person who is so confident with themselves, that they are impervious to any demeaning fat terms (fat jokes).
Person 1--- Look how fat that guy is , if I was that fat, I would never take my shirt off at the pool, what is wrong with him?
Person 2---- nothing, he just doesn’t give a shit about what others think, he’s a Fatmug.
A combination of a Fangirl (or fanboy) and a twatmuffin. Generally close minded overzealous fans who - upon realizing they can't win an argument - result to insults and general asshattery.
Guy one: Did you see that guy's rant on how 'awesome' Sephiroth is?