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. :)