Usually an emo with pointy (most often blonde, black, blue, green, ping or red) dyed hair. The not-so-rare specie of posefags usually puke to lose weight, they often use skinny jeans, have piercings and listens to lame deathcore. Their primary mating-sounds is pigsquealing.
PS. They're camwhores.
-"I bet he's an emo because of his lack of style."
-"Oh really? He looks more like a posefag in those skinny jeans."
-"Dude, is he a girl?"
-"Nah, he just poses like one!"
People who, whether out of mental/social dysfunction or excessive movie/book/game fandom, like to pretend (in a non-ironic manner) that they are vampires. Includes Anne Rice fans, fans of books about sparkly vampires, certain substrata of goths, and the sort of really strange people who post on I'm-a-vampire internet boards.
"Let's go to the movies."
"Oh, not tonight. That newvampire movie is out, and the place will be choked with the Poseferatu. I don't want some fat guy in a cape getting pancake makeup on my jacket."
This spelling should follow a more logical form, Puss from the truncated word Pussy. This slang refers to cats as an association to the female gender or female genitals and is used to describe a male that has been subjugated by a female or a male that does not stand up to the stature of being a male in the given social circumstance.
I would spell this word "Puss", as in Puss'n Boots or as in He's a Puss (Pussy) to spell it "pouse" so as not to offend the girls. :)