and is the act of gaping or keeping your mouth open while talking to someone, sitting there or pictures on facebook. Some girls suffer from this disease and you can notice it in real life quite often and if you look at their facebook profile you will be confirmed.
Guy 1: Yo man look over there at that chick staring at us.
Guy 2: HAHAHA that's some major PBFE right there!
I was talking to Miriam and even though i was staring at her boobs all the time i couldn't take my eyes of her gaping PBFE mouth.