Acronym for "Fandom Is A Way Of Life". Often used by fen to describe their level of interest in their particular fandom. Folks following the FIAWOL philosophy get deeply into their fandom, sometimes going to extremes to show their love. (Remember, "fan" is short for "fanatic". :)
If you wear a Starfleet uniform to a court date, you're most likely following the FIAWOL philosophy.