It is an adjective to describe someone of being very sneaky in Fortnite Battle Royale
A person that pretends to be loyal and loving to get what they want at the moment. After they do they turn cold and calculated. They use your insecurities to hurt you. Then pretend that their actions had nothing to do with you. They seem so kind but they're really sneaky slime.
Her: Let's go hiking babe
Him: I'm so busy this week babe
His Facebook story: Him and a different woman hiking
Her: Wow who is she? I thought you were busy. You just didn't want to take me you BIG SNEAK