An insult meaning big assed, or to have the mental characteristics of being an asshole
such as sassy would mean "having much sass", assy is literally translated to "having much ass"
This can also literally translate to "asshole", in the most common cases
Don't act so assy just because things didn't go your way.
Are you kidding me? They're going to start counting pluses on a 4 point grading scale? That is super assy.
Wow, Alexander was an assy movie.
Fred Phelps is the assiest person that I've ever heard of.