Typically a woman whose ass is large enough to form a bulge or lump that resembles a fat upper pubic area
Dude, her assfupa is so heavy and disgusting that last night the force was such that when we were done fucking, I walked away with my pubic bone crushed and my dick missing.
Similar to the term "party pooper". A Party FUPA is female at a party that ruins the party as a result of her being a dumb bitch. FUPA is term coined to describe the sometimes fat area above the female genitalia.
Arielle, will you please cut the shit. You are being such a fuckingPartyFUPA.