Derived from the Warhammer and Warhammer 40,000 universes, Humie is often used by the Orks to refer to Humans, (Imperial Guard or Space Marines). It is not necessarily in a derogatory tone but being orks, it usually is.
This may also be employed by ork fans in other fantasy or sci-fi games where Orks / Orcs are a playable race along with Humans, such as World of Warcraft, (though officially in the lore, WoW Orcs do not really talk like that).
Dem humies be wantin' a fight, we'll giv 'em a fight!
More humies for stompin'! I wantz da teef, don' touch da teef!