Phwooargh is a sound the British make in reaction to seeing or thinking of something attractive or especially ritzy.
Extra "O"s and "H"s and other letters can be added to the word to ad emphasis.
Kara: Wow, look at this picture of Brad Pitt.
Greta: Phwoooarghh. I would love to do him.
Reaction to Brad Pitt:
Reaction to the less hot George Clooney: