Broken acronym for "Hot Piece Of Ass", coined as part of a forced effort to create a viral web meme. Attentive readers not suffering from dyslexia will notice that this actually is an acronym for "Hot Of Piece Ass".
That's just sloppy.
Andy: "Hey, did you see that chick with the dry erase board on the internet? What a HOPA!"
Bob: "Seriously? You're actually using someone else's made up and poorly thought out acronym for this? As if there aren't enough ways to refer to an attractive woman already? for God's sake go to urbandictionary and get out of my sight.