Wow, my speech teacher told me to look up this word today, this was the homework, told the class to figure out the ancronym to the word, it's actually a backronym and here is my results:

1950,s NYC, urban black culture slang.
Pretty Hips And Thighs!
She's phat! Man (typically) speakes to another about a woman's (typically) voluptuous figure.

In the 80s, an 18 year old inner-city black kid from Richmond, Virginia told me that it stood for "Pussy, Hips, Ass, Tits", And he told me this around 1985. So that word is AT LEAST 27 years old. True Story. Just thought I'd share with you.
DAAAM That girl got some bangin phats Yoo!

I guess that it's the 85' verson huh?

XD