Public Display of Ass Action, not to be confused with PDA (Public Display of Affection). Used when couples or friends with benefits demonstrate public acts of voyeurism, fornication, and anything surpassing 1st base. It can be done alone, too, but is probably much less fun for the people who happen to pass by and for the said person undergoing PDAA.
Charlie saw them PDAA-ing and figured it was easy for the guy because the girl was in a skirt; he got a better view, too!
They were PDAA-ing in the library; it was some nasty shit, yo!
I want to PDAA, but I need to buy my rubbers and find a good public spot!