It is the combination of Wahh and Nigga. Wahh, is a phrase an Asian person says when surprised. Nigga, is what black people call each other as in homie. Thus, this is what you call Asian person with a black personality.
1) carlos: *stuffs watermelonon his head*
girl: "don't be wagly!"
3) girl 1: "why are you being so weird?"
Girl 2: "I'm not weird, I'm just to wagly for you"
A wagey is someone who works a, typically unfulfilling, 9 to 5 job for a paycheck. It is often used by people who are self employed to refer to people who work for faceless corporations.