Party Best Friend Term used to describe a one night "best friend" at a party. Usually seen drinking together, laughing, saying you will be best friends forever, then not ever talking after. You can always depend on them for the night.
Jenna: So I saw you hanging out with Emma last night. What's up with that?
Holly: Oh. She was just my PBF. We took shots together and held each others hair while we barfed. We stuck together all night.
My college kid kept asking me about healthy food options, and then asked if he could buy a CD on my Facebook wall page. Man, this PBF isn't helping us cut the cord!