It is used to describe the nasty dick sucking bitches that are worse then nasty and disgusting. For example skanks sluts and the whores that you know or go to school with.
It can also be used to describe something that causes you to say "eeewww!"
Person Two- "You got that right hewmmie! She slept with half the guys at our school!"
Person One- "Did you here about how Sabrina took a shit on some guys chest while having sex?"
Person Two- "Ewwww! That's MASTEY as hell!"