Abbreviation for Ageless Faceless Gender-Neutral Culturally Ambitioned Person. It is used in the computer game Zork Grand Inquisitor, where your guide asks your name.
Meaning is just to name any common and completely unknown person, as it says in the abbreviation
Guide: What's your name?
You: (you can't answer him, since he can't here you)
Guide: Okay, I just called ageless faceless gender-neutral culturally ambitioned person, afgncap, for short.