This is a person who, at a party, will be belligerently drunk, high, etc. This person will cause problems at a party, particularly party fouls (spilling things, knocking things over, etc). PDAs generally always make asses of themselves as parties; this is what they are known for. Many FYPs are PDAs.
Most commonly known as public display of affection these days. Includes kissing or touching and anything else to to do with love-oriented gestures in public.
"Sheesh, enough with the PDA! Go rent a room, you guys!"