Most Helpful Girl
I've never used that insult. But I have used "buttface" which I would think is pretty much the same. This may be strange but I would use it in more of a playful/teasing way. If I didn't get my way I would use it. It wasn't meant to be very hurtful. It could be used interchangeably with "stinker."
Most Helpful Guy
Just another shitty insult where someone inserted the word "ass".
What a bunch of asshats.