Abbreviation for F*ck It Let's Go! It's when you do something without thinking about the consequences, without planning for it, without knowing where to go or what you're going to end up doing. It's about not having any plans at all...
1. A: Wait, do you have protection?
B: Tsss, let's FILG it.
2. A: What are we doing for your birthday?
B: We're going on a FILG Trip. Awyeah...