From the meaning of a common cat, also meaning the same as minger.
Thus being that they look like one hell of a ugly mo-fo that they need there head sorting with a large metal bat or try on a paper bag on there head.:P
Moggy is to be in a state of absolute embarrassment or to look unpleasant. Also can be described as disgustingly good. Moggy can be a good thing or a bad thing it really just depends what mood your in.
A human/animal/anything in between who is fine as fuck, solid 10/10 and mogs everyone in their vicinity making them look clapped because of their perfect facial harmony and physique.
Giselle: OMG STACY THAT BOY IS SO HOT HIS FRIENDS LOOK UGLY CUS OF HIM
Stacy: YEAH HES MOGGY I DIBS